OK, here is the deal. Want to know why Amsoil and RP rate so high in many tests? They use extreme pressure additives in their oils to inflate the performance in tests. These additives have no place in engines. They USED to be used for older engines, but it's no longer needed. Instead, those additives should be used in applications like gears etc, where extreme pressure is an issue.

Secondly, extreme pressure additives are left out of many of the top brands because they promote corrosion. This is why, in some tests, like the out dated Timkin load test, RP, Amsoil, and a few others will out perform great companies like Mobile One, Valvoline...

So, back to the original issue. Stop over thinking, stop over paying, and just use a reputable synthetic oil and be done with it.

 

It won't hurt to use it, certainly not. The difference is, Amsoil OE is their lowest tier oil. It's only recommended to be used for the car manufacturer's recommended change interval, which for the 5.0 is actually 10k miles, I think. The signature series is their top tier oil that's suggested for 25,000 miles or 12 months. The OE uses lower base oil groups in it's blend.

 

The real difference: Amsoil $5-$10 per quart more... And I DO love Amsoil but I've switched the Stangs over to Pennzoil because my oil changes now are more time based than mileage based.

All of my 2-cycle engines use Amsoil products in the fuel/oil mix.

 

Locally;
Mobil 5w20 is $5.95/qt
Amsoil 5w20 is $7.50/qt

price is not really the issue since we are talking about less than $10 extra for Amsoil each oil change.

 

Thanks man

 

why is gas not thought about like oil? gasoline is a byproduct of the refinement of crude oil just like kerosene. when you buy ams or rp or any other oil, its not refined by them, they just buy barrels and add this or that and bottle it, slap a sticker on it and charge us extra for a brand when a blue bottle costs way more than a red or purple bottle. synthetic means there is more man made ingredients than oil. I may be talking out of my *** but im still going to use mc in my car. bash or prove to your extent