Re: Oil recommendations to use in a 427?
Sorry, you're right. My '63 owner's manual also calls for oil changes every 60 days. Back in the day I changed it every three months, which was about 3K miles and changed the filter every other oil change.
But things have changed since then. Base stock oils have much better oxidation resistance, and the additive packages are much better. That's why oil change intervals were extended as the years passed. By the mid-seventies GM was recommending 7500 miles or six months, whichever occurs first and new viscosity grades were added including 20W-50, which were okay for cold starts consistently above about 32F. (15W-40 is okay down to about 15F.)
Add to the above that we usually don't drive these cars every day, so mileage accumulation is slow.
For typical vintage car use where a few hundred to a few thousand miles are accumulated annually, and each trip results in engine operation for at least 20-30 minutes so the oil reaches normal operating temperature to boil off any crankcase condensation during warmup, I recommend annual oil/filter changes, and if the car is stored during winter, it should be done just prior to storage so fresh uncontaminated oil is in the engine over the winter.
If mileage accumulation is only about 500 and the oil doesn't darken, I think it's okay to go two years.
Acid formation is a function of the fuel's sulphur content, and modern fuels have less sulpher that decades ago, so acid formation is less of an issue, and CJ-4s have a higher Total Base Number than S-catergory oils, so they do a better job neutralizing any acid formation.
One of the best things that you can do is avoid short trips, and if you store the car over the winter, inside, let it be. Don't start and "warm it up" in the garage every month. That will just add engine wear and increase the rate of exhaust system corrosion. If you have a chance during the winter to take it out for a 20-30 minute drive, that's okay.
Duke
Sorry, you're right. My '63 owner's manual also calls for oil changes every 60 days. Back in the day I changed it every three months, which was about 3K miles and changed the filter every other oil change.
But things have changed since then. Base stock oils have much better oxidation resistance, and the additive packages are much better. That's why oil change intervals were extended as the years passed. By the mid-seventies GM was recommending 7500 miles or six months, whichever occurs first and new viscosity grades were added including 20W-50, which were okay for cold starts consistently above about 32F. (15W-40 is okay down to about 15F.)
Add to the above that we usually don't drive these cars every day, so mileage accumulation is slow.
For typical vintage car use where a few hundred to a few thousand miles are accumulated annually, and each trip results in engine operation for at least 20-30 minutes so the oil reaches normal operating temperature to boil off any crankcase condensation during warmup, I recommend annual oil/filter changes, and if the car is stored during winter, it should be done just prior to storage so fresh uncontaminated oil is in the engine over the winter.
If mileage accumulation is only about 500 and the oil doesn't darken, I think it's okay to go two years.
Acid formation is a function of the fuel's sulphur content, and modern fuels have less sulpher that decades ago, so acid formation is less of an issue, and CJ-4s have a higher Total Base Number than S-catergory oils, so they do a better job neutralizing any acid formation.
One of the best things that you can do is avoid short trips, and if you store the car over the winter, inside, let it be. Don't start and "warm it up" in the garage every month. That will just add engine wear and increase the rate of exhaust system corrosion. If you have a chance during the winter to take it out for a 20-30 minute drive, that's okay.
Duke
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