Amsoil makes some great claims about their synthetic oil, so does Mobil. I'd like to hear from you what your experiences are with either or both.

Matt in Moore Tafetta White 2008 HCHII

Very happy with Mobil 1. I can purchase it at the big stores such as Walmart or at the autoparts store. It is priced cheap when one remembers you can obtain 10,000 miles of useage. It runs well in cold (below zero F) as well as warm (above 90 F). A dealership even ok the use of this product in my vehicle.

I have never seen Amsoil in my part of the country.

2005 AWD Escape Hybrid
Best Interstate tank trip MPG 39.02 (scangauge II) for 402 miles on I-70, 10.3 gallons used over mostly flat terrain. Aug. 2007

Best Interstate tank trip E30 MPG 34.6 for 271 miles along I-80 in Indiana and Ohio. May 2008

Best multiple road tank trip E30 MPG 36.2 for 202 miles in Southwestern Pa. July 2008.

I've only used Mobil1, and I think it's a great oil. However, Amsoil is pretty good also. They're probably both very similar. At least similar enough to allow your guiding decision to be based on availablity and cost. Which one can you get relatively easily? If both, which one is cheapest? You're pretty safe either one you decide to get.

<Best Tank Economy!><Best Tank Endurance!>

I also run Mobil 1 but I am sure that Amsoil is very good. I do wonder though about a company who always compares themselves against the same oil (Mobil 1) all of the time. One thing to note, Amsoil does not have an API certification on all of their oils (that I know of). This might have changed since I checked on it.

When I was checking on oils, another good oil that was not certified was Royal Purple. This might have changed but I have not checked on it in a while. Mobil 1 became my oil of choice when I could stock one oil for all 7 cars that are serviced at my house.

At that time the company position was "it was too expensive to certify each oil". My position is if they spent some of their advertising budget on getting certified, this would not be an issue.

Amsoil DOES have some very vocal supporters however so be prepared for the blast when they read this post..... All that I know for certain is that any car requires a certified oil and at the time my research was done, Amsoil and Royal Purple were not certified by the API. I did not want a problem with Toyota if anything ever came up about my choice in oils.

Another satisfied Mobil-1 customer here. I have been using it for years. I have had the oportunity to tear down a few engines and measure wear on parts such as rod and main bearings. I have not done studies, and this is still just antecdotal data. But in my experiences the parts that this oil is meant to protect, is protected.

When my first oil change was due on my hybrid (Nissan) I used Mobil-1 0W-20 and immedietly experienced an increase in fuel mileage.

It gets late early out there. - Yogi

I have used both, and am currently running Amsoil XL in the TCH. Both are very good oils, I doubt you will see much difference in the two in wear, or gas mileage.

IMO, unless you drive the heck out of your car....keeping the RPM's high and redlining it often, i don't see the need for it.

i would rather change the cheap oil/filter every 3k miles vs. keeping the synthetic in there for longer (ie. 5k miles or yikes, 10k??). the synthetic oil doesn't break down as fast, but it still gets dirty. having all of that dirt sloshing around there for 5k-10k is probably worse on the motor than changing more often with cheap dino oil.

or if your car is high performance and you drive it hard. or if your car is new and you plan on keeping it for over 200k miles, then synthetics would help. but if you're going to ditch your car after 5 yrs, then all that synthetic money that went into it only help the next guy who owns your car.

I'm not sure you can get a 0W-20 in a non synthetic. But given how incredibly thin that oil weight is, I would not trust using a conventional.

Personally I always perform my own oil changes, so I can put in synthetic cheaper than most people can put in conventional.

It gets late early out there. - Yogi

For cars driven a normal amount, I think the cost comparison comes down in favor of the synthetic. The filter takes out any dangerous particles and 10,000 miles with synthetic is not a concern. I run Mobil 1 in the FEH (because it's always available and often on sale) and would use it in my truck if I drove more miles. The problem with the truck is that 10,000 mile intervals would be almost 2 years and I can't quite convince myself that's OK.

the only way to prove that the filter will keep out contaminants for the duration of 10k miles is to send the filter and an oil sample to a lab. until then, i would rather use cheap dino oil that's 1/4 the cost of synthetics and just change it more often. if you run synthetics for 10k miles, then you'd have to use the illustration of running dino oil for 5k. the cost would still be less for dino oil.

the biggest benefits of synthetics is viscosity breakdown. i don't see that happening in a normally driven car that's not raced.

take a high revving Honda S2000 that people keep in the 6000-8000 rpm in order to use VTEC....i'd definitely use synthetics on that. same with my 530hp Mustang with an $8k motor and $7k supercharger setup that feeds oil from the crankcase. plus i drive like a maniac and redlines the car often and doing 100-150mph often.