When cousins fight about engines - Third Generation F-Body Message Boards

all4u · 11-07-2009, 10:49 AM

OK, so this morning my cousin is "giving advice" to his car buddy on the phone. He mentions that for his 85 or 86 TA, (305 tpi, auto) he says with flat tappet cams, you should use an oil with more zinc. Ok, I get that, but he says that he is using Shell Rotella diesel 15-40! That is thick as heck! He says you can also use the common straight 30 weight. Um, hmm, won't he be blowing out gaskets and blowing the oil pump sky high? He says he has a mellings high volume pump and that he has nothing to worry about.

He is older than me and been working as a mechanic for a long time so I don't have much room to argue. I asked why he couldn't just use Castrol GTX 10-30 with a STP zinc additive. He said something like the additive fouls out the spark plugs and clogs passages. Huh? Someone please shine light on this.

Can you use a heavy 15-40 oil in a old TPI motor? Is he right about additives been bad for the car? Is diesel oil wise to use in a street driven car?

P.S. He also said that Hastings or AC delco oil filters are the best to use on a car. I have always been a K&N or WIX guy myself, am I wrong?

I've never been this confused in my life. I never heard of such "hacked up" stuff before. Please shed some light on this.

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kens86 · 11-07-2009, 11:08 AM

I only use wix filters. the problem with rotella oil is that it gunks up quicker in passenger cars with the more mileage that is put on the car. It works great for flat tappet cam break ins. It would be fine in your tpi for some miles. i wouldn't go 3000 miles with it, but a few hundred is fine. I run 10 30 valvoline vr1 non synthetic in my third gen.

Stephen 87 IROC · 11-07-2009, 11:17 AM

You can buy Rotella in 10W30 also. I use that in my truck. 15W40 won't hurt a gas engine but in cold weather, it's probably a little too thick. I prefer any brand of WIX filter over anything else.

The race car is a little different. I use Penzoil 25W50 racing oil and a System 1 filter.

Everything you ever wanted to know about oil filters can be found here. I won't use a Fram filter if it was free.

http://minimopar.knizefamily.net/oilfilters/index.html

all4u · 11-07-2009, 01:48 PM

Ok, so my choice in filters is half ok, I guess no one like K&N, but whatever.

My question is, can you run 10w30 rotella in a street driven, backup daily driver without causing problems? This is still assuming a flat tappet motor.

I use Castrol GTX high mileage in my 89 with a roller cam. I'm asking about my cousin's car. I thought diesel oil was not good for the oil filter.

Stephen 87 IROC · 11-07-2009, 02:52 PM

I just said I use Rotella 10W30 in my truck. It's a daily driver 12 months of the year. It's low mileage and I do 2 oil changes a year.

oil pan 4 · 11-07-2009, 10:46 PM

Where are you coming up with these things not to do?
Thick oil blowing out head gaskets or blowing out an oil pump?
Diesel oil having addtives bad for gasoline engines?
I have used Synthetic rotella in my car for quite a long time.
You are less likely to have problems running diesel oil in a flat tappet cam engine than if you run a modern oil with most of the Zn stripped out.

SBC oil pumps have a pressure relief valve built into them and the oil filters you use should have built in bypass.
In the SBC there are no oil passages through the head gasket. In some diesels like the cummins 5.9, yes.
In general the gas and diesels oils contain the same addtives, just different amounts and in the past the biggest thing diesel oils had was lots of acid controlers.
Its pretty much a known fact the K&N are a gimic, its more of a trash screen than a filter.
The STP addtive has a fair amount of Zn, in general more Zn or any other fuel or oil addtive can foul plugs, kind of like how leaded gas fouled plugs.
Last time I herd that STP addtive contained no detergent so there is a small possibility it could help cause build up where you don't want it.