Product Reviewed: SAE 5W-30 Signature Series 100% Synthetic Motor Oil (ASL)
Current Rating: 4.97 out of 5 stars
Votes & Reviews: 1010 vote(s) and 1476 user reviews.
Reviewed by Soonerfan: 
When I first started using Amsoil Signature Series motor oil I noticed that the engine ran smoother and fuel mileage improved by 1 mpg. Great product will use in my vehicles from now on.
Reviewed by Sergey the Welder:
Used it in multiple vehicles over the years, some being highly modified turbocharged cars. Latest betting LNF powered 2.0 K04 turbocharged Cobalt SS, HHR, and Pontiac Solstice 2.4L with aftermarket turbo kit. All of these ecotecs loved 5W-30 Signature Series and run way smoother than on OEM recommended Mobil 1 stuff.
Reviewed by Bills Ecoboost:
Switched to signature series a year ago. Minimal mpg improvement from tbe pennz ultra. Seems to quiet the engine noise but do not like how it turns black fast and has the dino smell. I flushed as recommended on first change. New formula this fall and hopefully improved
Reviewed by Keith:
Amsoil has the best product on the market. I use it in all of my car and even my small engine equipment.
Reviewed by TTurtle:
Use in all 4 trucks work and pleasure lawn equipment and Harley. Thumbs up
Reviewed by Miracle:
Absolutely Best stuff for extreme Arizona heat. Great piece of mind.
Reviewed by mcf:
I have used this product almost since the vehicle was new and enjoy the once a year oil change that this (and amsoil filters) allow. Now 200,000 kilometres and the engine runs like new.
Reviewed by Murffer:
I've been using Amsoil since 1979. I used it in all my 25 plus cars , 20 plus Motorcycles , 2 Tractors , lawn tractor , lawn mowers, my ATV , and my whole house generator . Boy am I hooked
Reviewed by MechMike:
I see the old reliable signature product I just bought has been reformulated for my next purchase. I hope Amsoil didn't fix something that wasn't "broke".
Reviewed by Rosco:
Being a new customer to Amsoil, I've read lots of good reviews and spoke with Amsoil Tech several times, and lots of satisfied customers before making the switch. I'm still a few thousand miles away before the first oil change and a oil analyst test. I also use Amsoil oil filters. With all the above sad, I'm very satisfied with the product and the help of all the technicians. Thanks.
Reviewed by None:
Using AMSOIL products for years and has never, never been disappointed, ever!!!!!
Reviewed by No name:
Only oil I've used
Reviewed by JB:
Best oil ever. Use in my oil burning jeep. Oil use has dropped considerably. Great product. Love it and jeep now.
Reviewed by AmsoilLifer308:
I use Amsoil in my Nissan Frontier, 4 wheeler and snowblower & lawnmower. I wouldn't use anything else. It never fails, always slippery, and allows high mileage between changes. I'm a lifer! Thank you AMSOIL!
Reviewed by George:
Amsoil Synthetic Diesel Oil is the only oil I use in my 2007 Dodge Ram 2500. Very trusted oil, good folks that work win.
Reviewed by Ron:
Good stuff
Reviewed by STONEY:
I HAVE BEEN USING AMSOIL FOR OVER 20 YEARS ON ALL BOTH OF MY VEHICLES. I HAVE ALWAYS USED THE EXTENDED OIL FILTER SINCEL IT HAS BEEN AVAILABLE.
I USE THE SAME OIL CHANGE PEOPLE EACH YEAR. THEY ARE ALWAYS SURPRISED THAT THE OIL IS NOT GRITTY OR THAT IT DID NOT BREAKDOWN . I WILL BE A LIFETIME PREFERRED CUSTOMER OF AMSOIL FOR LIFE.
Reviewed by Lou:
Whether it's my daily commuter or my weekend toy, I use AMSOIL to protect my vehicle's moving parts and keep it on the road.
Reviewed by Everything Ford:
I have been using this product from the beginning with my truck. I believe as a result I have not had any major engine trouble or turbo issues even after putting many miles on now
Reviewed by Tim:
I've been an Amsoil Preferred Customer for many years. Have used most all of the Amsoil lubricants and other products at one time or another. Have never been disappointed. Love the way Amsoil continuously improves its products, including this Amsoil Signature motor oil. Try it. You'll be pleased, too!
Reviewed by paybob:
Love this oil. Been using it since the truck was new at 20 miles. Now have 233,000 on it and absolutely no problems with the engine. Oil changes have varied between 10,000 and 18,000 miles. :)
Reviewed by Boswell:
I have been using Amsoil products for 25 years, and is very satisfied with everything.
Reviewed by Eric:
The best of the best work here and produce the best of the best products. I would pursue and career here if made possible.
Reviewed by Bill:
Engine has over 300,000 miles, absolutely no deposits inside as revealed by boroscope, change frequency is 12,000 to 15, 000 miles, 700 hours, this oil is simply the best
Reviewed by PO-BOY RACE-N:
Used it 4 years but it seems 2 seep through gaskets after years if use. No sludge build up 2 keep it from leaking out?????????
Reviewed by Doc:
I have been using Amsoil for over 12 years and am always impressed. The 5w30 Signature series never fails to impress. Darn never every oil change I am struck by how brown the oil is still after a years worth of use. Engine is always taken care of using Amsoil and I shall be using it for a long time to come!
Reviewed by Dutch:
Better than advertised, trustworthy, reliable products.
Reviewed by handyman:
I have used amsoil products in all the vechile i purschase over the years including my motor home some of the vechicles were diesel some were gas. i used it in them all.
Reviewed by Believer:
I began using Amsoil back in the 80's after reading their claims vs conventional oil.
After some years, I transitioned to one nationaly recognised synthetic I could buy at a big box store...it was
about the same cost, a little more convenient, and I reasoned, probably good enough.
In the process of time, I bought a 94 Miata. After some work, it ran well, nearly 30 mpg, but the lifters were noisey. To quite the lifters, I took each one apart, cleaned them, and reassembled all 24 of them with 10-40 high mileage oil of that one brand of synthetic.
Much to my surprise, the lifters were now much worse.
I immediately changed the oil to that same one brand, but 0-30. This made the lifters quieter, like they were before I cleaned them.
On a lark, I decided to try Amsoil 5-30 in the Miata. I could not believe the difference! I had done all that work, but all I needed to do was pour in a higher quality oil. The idle was now smooth and quiet; so much so that when I sold the car to another Miata enthusiat (advertising the smooth and quite engine at 185,000 miles), all they did before paying my asking price was open the hood to see the engine idling.
Amsoil.
I've seen it make a diffdrence.
Reviewed by Jason C:
I switched to amsoil in 2007 and have never looked back. It's the only Brand I trust in my vehicles.
Reviewed by JRobin:
I use Amsoil ONLY in my truck, car, Harley, and outboard engines!
Reviewed by T BEAR:
MY FAMILY ALSO USES IT HOW ABOUT THAT
Reviewed by Woodster:
I use the oil filter and the 25,000 mile oil for the mileage listed or once a year, whichever comes first.
The once a year always comes first for me.
Thanks for such a good oil.
Reviewed by Doctor D2:
Bought the oil. Best purchase decision ever. Engine is purring like a kitten, with the best mph ever.
Reviewed by Chopper:
I only came to know and use Amsoil from the previous user of my Nissan Titan. He stated he had used Amsoil in it after he bought it. Not wanting to change to a different oil even though I had always use Castrol or Mobile 1, I decided to check on this Amsoil oil he was using. I have to tell you I truly believe this has to be a better oil then what had been using in my last 45 years of driving! With all the testing that Amsoil does on their oil and what it goes in really impresses me at they know oil and they really truly know synthetic oil! I am proud to display my Amsoil sticker on my back windshield of my truck knowing that I am part of a elite group of guys that are wanting the best oil for their engines!
Reviewed by Daniel:
I've been using this AMSOIL for several years now. I saw immediate improvements in my daily commuter just from switching to their oil & filter
Reviewed by Tim:
I run the full line of Amsoil synthetics in all my vehicles, my F150 Ecoboost is my primary work vehicle, I drive 7 to 8 thousand miles a month, I am a regional manager with a multi state territory, Amsoil makes excellent products Ive never had any issues
Reviewed by PF:
I have been using Amsoil for over 25 years, although somewhat pricey, well worth it! I do oil changes every 10,000 miles and have put as much as 275,000 on my car without any engine knocks or breakdowns. I realize they recommend going 25,000 between complete changes, but I prefer to go every 10(k). This is the best of the best synthetic oil on the market!!
Reviewed by Jesus:
Excellent product, exceeds my expectations and I do change my oil and filters as Amsoil recommendations.
Reviewed by Tom:
Keeps my Jeep running good
Reviewed by Rick:
My 07' Toyota FJ Cruiser runs great on this product, much better than any competing brands. I use signiature series and put a high amount of miles on my truck in a very short time so I change my oil around every 5-6 thousand miles. Fast shipping. Good customer service. Definitely a quality product and a smart purchase for any vehicle owner.
Reviewed by Frontier man:
Regular oil for my truck.
Reviewed by Lucas:
This oil was purchased for a 2016 Corvette. They wanted the best, that's what they got
Reviewed by BobWol:
I have been using AMSOIL products since 1990. A mechanic introduced me and I have been using them in all of my vehicles ever since. As an example I started using AMSOIL in my 1988 4-Runner at 80,000 miles and at 225,000 no leaks and no burning. I have had occasion to call support to cross reference oil filters and have been very successful. Thank you!
Reviewed by Too many toys:
Yes Amsoil products in all cars, trucks, equipment, motorcycles, and a boat. Never had a problem. Had to do a top end rebuild on a motorcycle with over 300 hours on it. Valves were worn out but, the cylinder looked brand new! Amazing product.
Reviewed by Dave 300:
Since I switched to Amsoil in my wife's 1.6 liter ecoboost Escape it has been running smoother and quieter than with a competitor's oil.
Reviewed by RCinNM:
I first used Amsoil in my GMC Yukon XL. I immediately noticed the difference. More power and better gas mileage. Since then, I've been using Amsoil in every vehicle I own and everything I own that has a motor: tiller, lawnmower, chainsaw, trimmer, weedeater, pressure washer, 4x4 truck, small SUV and my GTO.
Reviewed by Tiger:
The product holds up under extreme heat and saves you repair cost.
Reviewed by Mike:
.
Reviewed by john:
excellent
Reviewed by Diesil:
I ave run amsoil 5w30 in my 05 2500 silverado for 12 years. Still runs like it brand new after 150,000+ miles. I change oil about every 6,000 miles and never had any wear problems or loss of power problems.
Reviewed by M.Winter:
I've used and sold Amsoil products for about 18 years exclusively, without one issue. At least 100,000 miles on three different cars and one almost 170,000. (2002 ML 320). Once a year oil changes are the norm.
Reviewed by cardi52:
I only use the best oil and it's this brand will always use this oil and only this oil best I've come across really makes my vehicle run strong!!!!
Reviewed by TerryRH:
Really smooth and quieted the motor a good bit. About 3k on this oil change and it still runs as good as the day I changed it. It hasn't started to break down like some other oils.
Reviewed by Gunner:
For maintenance in truck. My husband first used them in the 80's. Got away from Amsoil due to costs. Now back with them. Met a man who took a course just on oil products. Amsoil came out way on top., Now use oil, oil filter and air filter Amsoil. Have complete confidence in the superiour quality of these products.
Reviewed by Ode:
Use this in my truck engine. It's a great product. It keeps my motor clean.
Reviewed by Pipes p:
Ive been using amsoil for 25 years. Its pricey, but i pay it for a reason!
Reviewed by David the Adventurer:
I have used this in my gas fired cars and trucks since 2002, no problems at all.
Reviewed by CJNREMTP@28:
This oil is spectacular! Somehow I failed to check the oil level in my wife's '08 Honda Accord 3.5L V-6 and when I did check it, it only had 2 out of the required 4.5 quarts! ; o I have not noticed any damage to the engine system since and count my blessings as she would have kicked my rear if anything would have happened to her beloved car! Thank you Amsoil for such an awesome product!!! You are a wifesaver!!! ; ) This idiot makes certain to check the oil level in her car now!!!!!
Reviewed by Reg Coderre:
Very good product.
Reviewed by Erff:
Always use this in my vehicles. Best oil I've come across. Amsoil or bust
Reviewed by SDJazzMan:
I pulled into a gasoline station and they actually asked if I wanted them to check the oil. I knew it was okay but said - sure go ahead. When the attendant pulled out the dip stick I asked him to guess how many miles I had on that oil. He replied without hesitation and said that I had just changed it. When I told him that I had almost 5000 miles since I changed the oil, he couldn't believe it.
Reviewed by Jin:
C7 Stingray, 2017 Equinox ,, 2009 Vibe
Reviewed by charlie k:
love that i can extend oil change intervals
Reviewed by The hobbiest:
I change my oil every 15,000 miles because it has a 15,000 mile oil filter, I could go longer if amsoil made a 20-25,000 mile filter for my car. I use amsoil for my lawn equipment, motorcycle, and now to lube and clean my guns
Reviewed by Me:
I only use Amsoil. It is the best
Reviewed by George:
I purchased a used 1996 Chevrolet C2500 with 341,000 miles on it. The previous owner said that he only used AMSOIL. So I drove the truck for a thousand miles then changed the oil with AMSOIL. It must work, the truck has the original engine, original transmission and the original exhaust system
Reviewed by kirbstoy:
I know exactly how Amsoil will perform in my 2017, F-150, 3.5L/twin turbo. I have used Amsoil for decades and have never had an oil-related problem with any of my engines. Amazing chemistry...that's for sure.
Reviewed by Exceptionmode:
Simply perfection in motor oil.
Reviewed by Titsmcgee:
Have a 5.3 that I bought did first oil change and ran valvoline full synthetic burned 2qts in 2000 miles. On my 5 oil change with amsoil and burned 1/2qt in 3000 miles. 5.3 are known for burning oil due to oil injectors clogging but running amsoil seems to have made a huge difference.
Reviewed by El viejito:
I buy this oil for my family SUV and so far is doing the job done
Reviewed by Francis Gamache:
I've never seen a better product than Amsoil! When you use the Amsoil oil you can hear and see the difference at the first use! I recommend to all my friends and family members!
Reviewed by Jim:
I use it in all my vehicles. Since none of of them go over 25,000 miles per year, I change the oil every March with Amsoil filters. The engines stay clean and, along with occasion PE, they all run very well.
Reviewed by Bullman:
Use in all my vehicles, and it definitely helps with the fuel economy.
Reviewed by Bullman:
Use in all my vehicles, and it definitely helps with the fuel economy.
Reviewed by Lee:
Normal, quick, and easy order process and quick receipt.
Reviewed by Gi:
I've tried all brands of oil from Mobil1 to Royal Purple and by far Amsoil is the best. I can really feel and see the difference. My engine runs cooler with Amsoil and even when I changed it at 25,000 miles it still looked better than all the oils I tried and I changed them at 5,000 miles.
Reviewed by Heal:
Great oil I change out at 7500 on a GMC Terrain 3.0L. Never had any problems summer or winter. I have 50,000 on engine no serious issues with engine other than regular oil changes. Very happy with this oil
Reviewed by Popo:
The enginer runs so much smoother.
Reviewed by Charlie TUNA:
Been using in my 2004 Chevy Silverado for years!! Works great.
Reviewed by SwanyWI:
I've used this oil in my 2004 Caravan from the point of new. I used it for work and changed oil in the 20,000 to 25,000 increments. The van now has 247,000 on it an it leaks a tiny bit but uses none. At 8,000 miles I need to add 1/2 a quart. No problems here and I use it in all my vehicles and equipment.
Reviewed by Pizza:
I was using another full synthetic because that's all I could find in our area. Noticed the other brand would burn off and I'd have to add oil about every 2nd tank of fuel. I switched to amsoil and the burning off stopped. Noticed no difference in fuel mileage or HP gains but like I said, I was already running a full synthetic.... Good stuff!!
Reviewed by Jr:
I use only Amsoil in all my vehicles including my garden tractor. I use the oil, power shot, the Amsoil oil filter's etc. I love it for it's protection and the life of both the oil and filters. The power shot is the best stuff on the market to protect your small engines from water and ethanol. It keeps the system and carburetor clean. I had problems with water until the power shot and never again in the past 6 years. I wish it was in a bigger bottle at a better price cause the small one goes so fast. I live on a budget but make sacrifices to buy all my Amsoil products for my tractor and car and truck. I tell everyone to buy it and have most of my son's using it. The oil last so much longer in both vehicles and especially my garden tractor.......I use to use Valvoline but only now for top off if I don't have Amsoil. The large stickers are on my vehicle engine covers and on my tractor engine cover so others can see and know to a mechanic nothing but Amsoil goes in my engines and gas tank for additives......
Reviewed by Dave:
I use Amsoil in everything, so perhaps I'm a tad biased. But the 5w30 Sig Series does great in my Mazdaspeed Miata turbo & Ecoboost F150!
Reviewed by AcuDoc:
Much better than expected.
Reviewed by The Celica Driver:
I use Amsoil signature series 5w-30 on my Toyota Celica GTS and it makes my car runs great. My car is around 250k miles and I don't have oil burning issues on my vehicle. During the winter time it starts smoothly and it doesn't hesitate to crank. Oil intervals can go longer than 4k to 5k but I usually change them at that point since I drive over 70 miles a day in rush hour. Great oil and great pricing.
Reviewed by JJ:
I used this in my '15 WRX which requires a high shear stability, synthetic oil. This oil was recommended by many websites and forums as one of the top oils you can use. Worked great while I had the car but I plan on putting it in my new Infiniti as well.
Reviewed by Horse-n-heeler:
I have been using Amsoil for over 35 years. Our current commuter car (120 miles per day) has 265K miles and still runs like a top. Uses very little oil (less than a qt per change)
Reviewed by none:
I use amsoil, car, pickup, equipment, lawn mowers, tillers, and chainsaw. Protects engine and less time changing oit.
Reviewed by Carlitos:
I have a 2008 Lexus v6 and recently checked mileage on 300 mile trip.
Checked and double checked, 34 plus MPG. Amsoil Signature in motor with KN Air filter. VERY IMPRESSED!! Carlitos
Reviewed by M8ttix:
Used to run this in my stock sti motor. Now it's built and I run the 5w40 Euro. Love all your stuff never had a issue.
Reviewed by Timber:
Have used AMSOIL OIL for years. 2003 SVT FOCUS has 332,600 miles on it. 2011 SAAB has 105,200 miles on it. Excellent products.
Reviewed by Barney:
While I was apprenticing to be a mechanic in the early 1980's a friend of mine challenged me to a comparison test between Amsoil 100% synthetic motor oils and conventional oil. As a result, I switched to Amsoil and have used it for over 30 years in all of my 4 stroke, 2 stroke, and diesel motors. It lasts longer, doesn't have the viscosity break down, and is a better lubricant than other oils.
Reviewed by Robert:
Been using this oil since 2000 love it
Reviewed by Pdizzle:
I have been using this product since I bought my low milagr 2004 Mustang cobra back in 2013. I have trusted this product to protect my factory supercharged motor and it has done a great job. Happy with all my amsoil products. Loved there oil in my ATV's when I was younger and now I use there stuff in everything.
Reviewed by Moparsean:
I run this oil the full year or 15,000 miles as i fall under severe service useage guidelines. It has always kept the inside of engine clean and i rarely add any oil,it performs well,oil analysis comes back great. Both vehicles i use it in have high miles and i know its keeping them running well. Highly recommended. Amsoil is the best oil in my opinion. I even use amsoil in my lawnmowers. Synthetics are not all equal. This is the best out there. I wrench for a living and have seen the effects of using sub par oil.
Reviewed by Vince:
My car has 140k miles and I've been changing my ea amsoil filter every 10k miles (rated for 15k miles) and my oil in my vehicle every 20k miles (rated for 25k miles) without fail. Excellent results and cheaper in the long run when compared to other conventional products.
Reviewed by Q:
I've been using this in all my vehicles since 2010, I'll never use anything else again. I do yearly changes and even after being in the motor for that amount of time it still has a bit of color.
Reviewed by LGC driver:
Have used AMSOIL exclusively for 15 years in my vehicles. Have never had an oil related issue.
This oil is especially good in my F150 eco boost engine. Smooth, quiet, economical performance.
Best of the best!!
Canada
United States
Love it
Have been using Ams oil for years especially in my 2011 Kia optima which now has 226000 miles. Die to the extended drain intervals has saved me lots of money and my engine still runs like the day I bought it.