Royal Purple vs Amsoil, and what's synchromesh?

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04-12-2014, 10:02 AM

#21

moosestang

6th Gear Member

Join Date: Sep 2006

Location: Gainesville, FL

Posts: 11,278

Quote:

Originally Posted by Art161

I would use the type of engine oil that came with the car until at least 7500 miles. Until then, use full synthetic only if the car came with that from the factory. Otherwise the rings might not seat properly.

After 7500 miles, use full synthetic if you want, but stick with the weight specified in the Owner's Guide. Also, I recommend using only oil that has the API seal of approval. Manufacturers give all kinds of reasons why they sell oil that is not API approved. In some cases, the real reason they don't have API approval is because the oil contains more phosphorus than API will approve. Phosphorus is wonderful for keeping the engine clean, but it can kill catalytic converters.

phosphorus doesn't keep the engine clean, it's an anti-wear additive along with zinc. I'd rather wear out the cats, than the motor. I use RP 5w30 hps in my supercharged 4.6. The manufacturers recommended oil viscosity is for the best mpg, not the best protection. Using a thinner oil like 5w20 means more oil gets burned, that's why they are taking out the zinc and phosphorus. They have to meet that 8 year federal warranty on the cats and still get the best possible gas mileage to meet CAFE. It all makes me sick!

Calcium is a cleaning agent in oil.

Last edited by moosestang; 04-12-2014 at 10:37 AM.