My 1999 C5 has 20,000 miles and I dont drive it much
My question is how often should I change the oil??
Is Moble1 the reccomended oil?

 

Mobil 1 is the recommended oil, as per oil change interval that depends on mileage and or time, I change oil once a year as I also don't rack up to many miles on my C5.

 

Exactly what I use and do for my '02.

 

https://www.mobil.com/en/lubricants/...ight-motor-oil
0W-40 Supercar is the current recommendation but go check out the tool. Lots of good information there.

 

My head hurts.

 

oil selection is like opinions - everybody has their own preference.
Mobil 1 is just the factory-endorsed brand (i.e., they paid for sponsorship); you can use whatever you want that meets the intent of the owner's manual, page 6-15:

"Your vehicle’s engine is filled at the factory with a Mobil 1 synthetic oil, which meets all requirements for your vehicle.Substitute Engine Oil: When adding oil to maintain engine oil level, oil meeting GM Standard GM4718M may not be available. You can add substitute oil designated SAE 5W-30 with the starburst symbol at all temperatures. If temperatures are above 0°F (-18°C), you may substitute SAE 10W-30 with the starburst symbol. Substitute oil not meeting GM Standard GM4718M should not be used for an oil change."

if you sift through the thousands of other oil recommendation threads around here, you'll also run across comments from one of the engineers who was involved with the C5's oil life monitor programming, and his take can be boiled down to simply changing it when it says so due to the plethora of factors it accounts for. granted, if it's just sitting for a long time, it's worth changing on principle.

i've personally used Castrol & Rotella synthetics in both 5w30 & 5w40 over the years.

 

If you do not drive the car enough to get the oil life monitor down to a percentage where the oil change is needed, at least change the oil once a year. It is what is recommended in the owner's manual.

 

I have been doing once a year or every 3000 miles.
also been using Mobil1 from day one but any good full synthetic will make the car happy

 

One thing to keep in mind, is that the EPA has been requiring the oil makers to alter their additive packages, over the year. Therefore, the Mobil1 that's sold today, isn't the exact formula as the Mobil1 that our owners manual was recommending....

 

What EPA requirements are those?
Are there any other reasons Mobil changed their formulation over the decades?

 

...and what does that mean exactly? Spoiler alert....nothing to 99.99% of the corvette owners out there. For the vast majority, they could run non-synthetic oil from Walmart, and never have an issue......ever.

 

I use Amsoil and change my C5 oil every six (6) months, regardless of mileage. Oil is cheap, motors aren't.

 

You just joined last month!!!!

 

I would NEVER use Amsoil!! I just hate their "illegal" pyramid marketing scheme.

 

Who are you guys saving these cars for? I recently acquired a Corvette and I’m shocked by the importance that’s given to miles. Drive these things while you can.

 

Me. I’m a millennial and the C5 was the car I had posters and models of in my room when I was a kid. Now I have a near factory fresh M6 coupe example that had 25k miles on it when I got it. Couldn’t be happier

For oil changes Mobil 1 5w-30 once per year or every 3k miles because I do take it to redline

 

Thats awesome, hope you enjoy the hell out of it.

 

LOL!! Doesn't mean he hasn't been following for years...

 

Pick a brand and you can find someone, somewhere will have a horror story about that Brand X oil-WHATEVER. Proper weight/viscosity is what is most important over Brand loyalty. Proper additives are important too, especially in the rear diff.

I find it hard to believe that changing brands makes a difference in engine issues unless they are changing viscosity and/or the additive package is drastically different than what was used prior. Oil threads! This could be one of the motorcycle boards and when it comes to oil, the threads always seem to be similar!

 

It involves the reduction of zinc (ZDDP) levels in motor oil, as the zinc supposedly "taints" the catalytic converters, over time, supposedly reducing their effectiveness. This has been mentioned in numerous oil discussions, here on the CF.