What weight oil for a GM 350 HO crate?
 

There have been lots of threads about oil (dino vs. synthetic, high zinc vs. low zinc, etc.), but I didn't notice any experience or opinions for GM Performance crate engines, specifically for the 350/330 HO.

I have less than 12K miles on my 350 HO. I live in Minnesota, so high temps >90 are not a big concern. My temp guage rarely goes above 200 degrees. Heat is not a problem. I don't have catalytic converters (no emissions testing in MN), so zinc fowling up the cats is not an issue. I don't drive my '80 real hard, but I do like to leave my mark on an isolated strip of straight road near our house and I occasionally like the sound of full length headers, true dual pipes, and high flow mufflers at 3000-4000 rpm.

So, what oil do you recommend? I have been using Mobil 10w30 or 10w40 because I thought it offered the best lubrication. I use Rotella in our mint-condition 60K-mile '93 Turbo Cummins Dodge pickup (2 gallons per oil change!) but I never thought about using it in my 350 HO.

I'm open to suggestions. What do you recommend? :bigears

BTW, I only use WIX filters.

Rotella ok...as long as you are feeding it zinc for the flat tappet bump stick...(cam)..not sure about % zinc in the Mobil though....you might check their ZDDP additive package..

It's pretty hard to go wrong with 10W-30. Being sensitive to the zinc/phosphorous issue, I use this CH/SI oil in my 1967.

http://img.photobucket.com/albums/v1...y97/CTCoil.jpg

I don't think there is any zinc in the mobil but the shell rotella has it. I run 10w-30 val racing oil w/zinc. only have less then 1000 miles on the new motor. Next spring when I wake the beast up I'll switch to 10w40 or 20w-50 racing oil or rotella-T. Search the old threads there is a good one concerning the best oil to use.

Mobil 1 :thumbs:

I have a 350HO in one of my cars with only about 500 miles on it. It has 10W30 oil in it with GM EOS added. GM took the EOS off the market for awhile but has released a reformulated version now...supposedly with less ZDDP in it than before.

The manager at my local Chevy dealer said EOS is nothing more than GM's version of STP, but I don't know if that's accurate. Either way, STP does have ZDDP in it. The STP red bottle has more ZDDP than the blue bottle, but either should be sufficient of you can't find Shell Rotella or an equivalent.

Does that motor have a flat tappet cam in it? If so I use VR1 valvoleen.

i use 10w-40 standard valvoline in my 383 (10 yrs now) my 350 in the camaro and in the 327 in the vette.
i have heard that the heavy(thick) racing oils wont circulate as fast on start ups etc.. giving time for cylinder scratching etc..
unless your running it in the 1/4 mile alot i would use a good 10w-30 for breakin and winters up north and 10w-40 in the summer. jmho

At your point- Royal Purple 10w40. I've got an pretty extensive oil test PDF if you want it. send your e-mail. C.

The GM 350 HO DOES have flat tappet cam. The ZZ4 has a roller.

PM sent. Thanks! :thumbs:

Hey can you shoot me that PDF? Mpett1@netzero.com

Thanks

The only sensible response is to use a good quality synthetic oil...especially in Minnesota. Temp changes will "age" regular oil pretty quickly [oxidation]. Synthetics last longer and keep their viscosity better over time. If your engine has leak 'problems', they could be worse if you go to synthetic; if your engine is sealed well, there should be no problem.

The stability of synthetics is the main reason I use Mobil 1, but they have to meet ILSAC GF-4 phosphorus (ZDDP) requirements. Another post in the Tech/Perf section on flat tappet cams contained a link that lead to a table that shows the level of ZDDP in each of their oils:

http://www.mobiloil.com/USA-English/...duct_Guide.pdf

It looks like I can have Mobil 1 and ZDDP if I just switch to a different Mobil 1 oil. :thumbs:

Mobil 1
 

I have a ZZ3 in my Nomad and use 10W30 Mobil 1. When I switched I saw a very slight increase in gas milage and no consumption between oil changes. The motor only has about 12K miles on it so I change the oil by time not milage. There may be better choises out there but I don't think you can go wrong with the Mobil 1.

Changing synthetics by "time" is fine, if you don't mind the expense...but it kind of defeats the purpose of the synthetic oil. It doesn't oxidize like organic oil, so changing it based on time is really unnecssary. Even if you choose that approach, synthetic is still the best choice.