I have an 86 iroc z w/ lg4. I am concerned about the zdp additive issue. I have been informed that zdp has been reduced leaving older engines subject to scuffing and wear. STP has zcp.. I called them and that is what the customer service rep said. Anybody have anything to say about this issue?

 

Use an oil in 5W-30 or 10W-30 with a CI-4 + and SL rating. That's diesel and gasoline ratings, and will have the ZDP your flat tappet lifters need. The SL gasoline rating is better than what was available when our cars were new.

STP may have the ZDP, but it is primarily viscosity index improver - the first thing to break down under heat in an engine oil. Result - poor lubrication and sludge/varnish deposits. You'd be better off using the diesel oil.

 

I'd rather spend an extra $10 or so at each oil change than risk mechanical woes. For my '82 camaro 350's next oil change I'll be pouring in a bottle of Trick Flow's supplement. It's not quite so thick with ZDDP as a bottle of COMP CAMS' break-in lube.

 

Honestly, I wouldnt worry about it on a stock cam/valvetrain. The valve springs were pretty weak on those engines, and the cam profile is hardly an aggressive one. Flat tappet cams failing is because of the aggressive profiles and high spring pressures - those are the ones that really need the ZDDP additives. Slow, lame profiles like the LG4 cam with it matching 75lb springs won't have problems with 'normal' gasoline or diesel oil.

 

I can agree with that. In my case, my 350 has 100-pound springs, and the cam has been changed to a Crane HMV272. I considered Shell Rotella-T, but I wouldn't learn anything new that way. Besides, this option is a dollar less per oil change.

 

I only have one flat tappet engine left, the 396 in the '57. I've been using AMSOIL 5W-30 heavy duty diesel synthetic in it. That's with a Comp XS282S solid lifter cam and beehive springs. Change it once a season. The inside of the engine stays sparkling clean, and all I have to do is check the valves - they don't change.

The engine was built in 1997. I've raced it every season except 2000 (the transmission needed a rebuild and I just didn't have the funds to do it that year). I haven't kept really good track of the number of runs I've put on it, but it's at least 200 a year (more like 400 in 2004). It just keeps on ticking.

When you use an oil that has everything you need, you don't have to worry about unintended interactions between your oil and your additive. There isn't an oil supplier out there that will stand behind their product if you put somebody else's stuff with theirs in your crankcase.

With AMSOIL, I just know that I don't have to worry about my oil.

 

Good to know. The more proven-good options we have, the better.

 

hey five7, good to know there is oil out there ya can trust. I've been reading around about oils, and racing oil has plenty of zddp stuff in it. I heard rotella is weening it's self off the zdp concoction also.

 

Racing oil is good, but most commonly sold in 20w50 or similar/heavier weights. There is 5w30 and 10w30 racing oils out there, but they can be a challenge to find in some places. They work well in older engines though.

A really good quality synthetic oil, diesel or gas, is a good choice as well. I broke in my 350 (flat tappet w/ XE274 cam and HEAVY double springs installed after break in) with some 15w40 conventional diesel oil with a bottle of GM EOS. After that I used the 15w40 stuff untill the next oil change and have used either a 5w30 or 10w30 synthetic since then, and I have had no problems with it at all. That was about 3-4 years ago. I'll be staying with synthetics in that engine, and I have used synthetics in my LT1 since I got it a few years ago. Change both around 5000-6000kms and it still comes out looking pretty clean, just a little darker than when I put it in. Inside of the 350 is spotless. LT1 I havent opened up yet, but I'd bet it looks good too.

 

I found out since my original post, that Brad Penn (i think i have the name right) is the old kendle formula @ about 5 dollars a quart. Lots of zddp in it as well as detergents for regular street use and regular change intervels. Even if I used off the shelf oil, and used an additive, it would cost the same w/ the more expensive oil. I might try it. Also it stands to reason that the zddp would protect the other bearing surfaces like the cylinder walls and rod and main bearings as well. Even in a stock LG4.