What would be the best oil to use in a 1988 K2500 Chevy truck with 350 engine? Is 10W-30 Ok or 5W-30? I’m in Southern VA.

 

I have a 88 K1500, 5.7. I’ve owned it for 16 years. I brought it with 69k on it. Over that time, I’ve used both. Oil is a highly opinionated topic so you’re likely to get a million opinions.
The more important issue for me has been frequency of oil changes.

I change oil in my vehicles every 3k using a good quality filter. Keep in mind. It wasn’t that long ago Chevys came without any oil filter and multigrade oil wasn’t invented yet.

Im not sure but I believe 10w-30 is what is called for but I’m not good at following directions.

 

My 1996 5.0L V8 calls for 5w30 engine oil, and I am seeing that listed as the recommended engine oil for the 1988 5.7L engine as well. I use the high mileage version (Castrol usually) and am currently sitting at 201,800 miles on the odometer.