Glass Act

I have just completed a complete rebuild on my 1979 350 L82 motor now producing 375 hp. It seems I getting mixed answers on which motor oil weight to use. Everything from 10w 30 to 20w 40. Since I only drive my vette during the summer with 70 to 90 daily outside temp's. I'm wondering what others are using.

zwede

I'm driving my 454 year round including 100+ Texas summers on Mobil1 10W-30. Have 2000 miles since my last oilchange and have not used any oil yet (dipstick still reads full).

goinbroke

Markus, just curious as to what oil change intervals you're going with on that Mobil 1. This is the M1 synthetic....correct?

zwede

Yes, fully synthetic. I go 6-7k miles. Could go more miles but that is about a years driving and I don't want to go over a year between changes.

79Cruzer

I've been using 10W 30 in my '79 for 3 years now with no problems. I drive the car about 4000 miles/year (around mid April to end of October) and change the oil/filter about now then just before I retire the car for the winter.

Techno

Oil pressure.
If what your running gives you good oil pressure stick with it.
If its a tad low increase weight and a tad high decrease weight.

marshrat99

Sounds like you "tweaked" you L82 a little Anyways, as everyone has suggested, the 10W30 or 10W40 is a good range for the situation you're asking about. Be sure to only use non-synthetic for the 1st 2K miles to ensure your rings get run in.

goinbroke

Thanks Markus. I've heard of many M1 users with OCIs well past the manufactures recommendation...double the mileage in most cases. I often visit (lurk) a forum dedicated to lubricants, filters, etc. 7K to 10K M1 OCIs are common. I've seen a few going as high as 15K but they are doing a filter only change at around 7500 and often using a high density (filter media) filter like Purolator Pure1.

zwede

Oh, I wouldn't think twice about going 15-20k miles on M1 or any other high quality synthetic. But besides miles, time also breaks down the additive package and contaminates the oil and everything Ive heard says you want to change it every year.

I use a one quart filter. Used to run the PF35 until it got replaced with the PF1218. Ran that until recently changed the 1218 to a cheap piece of junk. Currently using some PF35L's I found. Not sure
what I'll use once the PF35L's are gone.

goinbroke

Markus, this is the forum I was speaking of if you're interested.
http://theoildrop.server101.com/cgi/ultimatebb.cgi
Pretty interesting place......they do a lot of testing and comparing.

RC73

Simple answer: 10W30 . Covers a good ranger of temps. That's what I use here in Texas and it get hot here.