C1 mileage between oil changes

[Johnny C.]

Hi there, for C1, how many miles recommended before oil change?

[Owen L.]

Re: C1 mileage between oil changes

If you really do enough driving of the car to do oil changes by miles, then 5000-7500. Oils today are much more highly refined with better additives. Even 7500 is a pretty conservative figure.

My engine builder who machined and assembled my '72's original engine said to change it out every 2-3 years — in that time frame the car will be lucky to clock 1500 miles. The issue with engines that don't get a lot of miles is that condensation can collect inside the block and contaminate the oil between changes. With this schedule you want to only run the engine when it can become fully warmed up so the condensation inside the block will evaporate.

[Duke W.]

Re: C1 mileage between oil changes

Regardless of oil quality the problem with most C1s is poor crankcase ventilation that allows the oil to be contaminated will little use. Owner's manuals from the era probably say every 3000 miles or three months, whichever occurs first, and this recommendation is based on year-round daily driving.

Vintage cars probably "time out" before enough mileage is accumulated. If you drive a few hundred to a few thousand miles per year and the car is kept inside when not in use, every one to two years is probably a good interval for engines with a well functioning PCV system, but maybe every year for C1s with just a road draft tube. Use any API certified 15W-40 CK-4 engine oil. Brand makes no difference, and don't start the engine unless you plan to drive the car and always drive it long enough to get the engine fully warmed up and at operating temperature for at least 15-20 minutes.

If you store the car during the winter, the best time to change is just before winter storage. The clock doesn't run on fresh oil in the crankcase during winter storage, and don't start the engine until you're ready to put it back in service in the spring.

Duke

[Leif A.]

Re: C1 mileage between oil changes

Dino oil every 3000 miles...synthetic oil every 10-12000 miles. Or, once a year whichever comes first.

[Duke W.]

Re: C1 mileage between oil changes

So if you have a vintage Corvette that you drive no more than 1000 miles a year you recommend only changing a synthetic oil every 10-15 years or more? Most synthetics oils are S-category that lack sufficient anti-wear additive for sliding surface valve trains, but 5W-40 CK-4 qualifies.

Duke

[Leif A.]

Re: C1 mileage between oil changes

Duke,
My recommendations are what I do personally for both my vintage Corvette and my daily drivers. I should have added a caveat (which I will).
I will stick with my mileage recommendations but add "or once a year, whichever comes first".
My '67 Corvette gets driven about 6000 miles per year so I change the oil and filter twice a year. My wife's BMW and my daily driver BMW get driven about 10,000 miles per year so I change the oil once a year even though BMW says I could drive it more miles before changing. Just my personal preference...works for me.

[Johnny C.]

Re: C1 mileage between oil changes

Thank you all for sharing your expertise.

[Duke W.]

Re: C1 mileage between oil changes

Duke,
My recommendations are what I do personally for both my vintage Corvette and my daily drivers. I should have added a caveat (which I will).
I will stick with my mileage recommendations but add "or once a year, whichever comes first".
My '67 Corvette gets driven about 6000 miles per year so I change the oil and filter twice a year. My wife's BMW and my daily driver BMW get driven about 10,000 miles per year so I change the oil once a year even though BMW says I could drive it more miles before changing. Just my personal preference...works for me.

Thanks for clarifyilng. Most manuifacturers have a mileage/time requirement, whichever comes first for fluid changes.

I believe GM recommends an annual oil change on modern Corvettes for warranty coverage if the car is not driven much and the oil quality monitor doesn't recommend a change within a year.

Duke