oil change

SCmeGo

Registered User
oil & 10% pulley
I bought a 90 SC in June; all I have done so far is the exhaust
2 1/2 into 3 into 2 1/2 no cats with a Dynoflow resonator, I will probably go with a 10% pulley. Will this be OK as far as head gaskets?

Also it's time for my first oil change, the previous owner ran synthetic 5w30 this seems a little week to me as I live in a warm Climate (Florida) any suggestions as to what weight would be best? I was thinking 20W40 synthetic. 80,000 miles

Any suggestions or input appreciated.

Scott
 
Scott
I am running synthetic 5-W30 I am in Canada so climate is a little cooler but i have heard some guys talk about leaks when they switched to synthetic oil i haven't noticed any yet so the jury is still out anyways

As for the 10% pulley that is out of my reach I have read alot of posts about it and the one thing everyone says is that make sure you do the exhaust first and open it up

anyways good luck
 
well I use 10w30 castrol some use 15w40 in worm wether now the 10% is all up to how you feel if you think it will last or not if the car has a lot of miles I would real think about it first on my car the most I would but is a 5% just how I feel
 
Hello

The exhaust modifications you have mentioned sound adequate for the increased backpressure of a 10% pulley, as you have eliminated the main bottlenecks; stock cats & stock resonator. I agree with the use of a 5% pulley, for long-term reliability of the Eaton m90 Supercharger and the fact that the difference will not be highly significant, especially when taking into account the extra power draw from the engine to turn the SC faster.

As far as the oil, a 20w40 should not be used in a stock-build engine, it is too heavy. Due to the high compression and power output of these cars, I would continue the use of 5w30. You could switch to 10w30, but it would possibly promote more wear at startup and reduce fuel economy. There is no reason to switch to a 40, however. Unless the engine uses significant oil, follow factory specs and keep it @ 5w. I recommend Mobil1 5w30 synthetic; it is among the best and few true fully synthetics.

As far as leaks associated with synthetic oils, these are almost always caused in older engines, with many miles, (100,000 for example.) What happens is the original dino oil is dirtier than synthetic and leaves debris deposits in the seals. Eventually, these build up and damage the seals, but fill the gaps to stop leaking. When such an engine is switched the synthetic, the cleaner nature of syn oil will actually remove the deposits caught in the gaskets. This will cause leaks if the gaskets were previously damaged. Some synthetics have a better rep than others for this, Mobil1 is associated with the fewest leaks. Usually, however, this does not occur in engines that are well maintained with regular oil changes @ 3000 miles, or lower mileage engines. Hope that helps. . . .
 
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