Fuel opinion and additives

[Hib Halverson]

Originally Posted by SteelBlueZR1

Regarding recommendations on engine oils and ZDP contents, if you haven't read Marc Haibec's tech paper, you should check out:
http://www.zr1specialist.com/HAT%20W...5%20Engine.pdf

I've read Marc's article–several times. I read it when he first published it in the newsletter and, then a couple more times when I was researching my article on engine oil.

Marc and I agree on many LT5 issues but the idea that LT5s have a problem with lower levels of EP additives in modern engine oils is not a subject on which he and I see eye-to-eye.

My research showed that because the LT5 uses direct acting flat tappets--meaning the cam lobe moves directly on the lifter face rather than on a "finger follower"--the loads at the lobe/lifter interface are far lower than those present at the same interface in an OHV engine. Because the loads are significantly lower, the need for EP additives is less and OHC engines with direct-acting tappets don't have problems with the lower levels of EP additives in modern oil.

This is why engine failures due to reduced levels of EP additives in engine oils have occured only in OHV engines (Small-Block V8s, Big-Block V8s and other pushrod engines with flat tappet cams) or in OHC engines where the lobe acts on a "finger follower".

There are tens of millions of OHC engines on the road worldwide which use direct acting flat tappets. If that type of valve train had a problem with reduced levels of EP additives in ILSAC GF4 rated oils, we'd know about it by now because there would have been widespread failures of cams and lifters in all those engines.

Further, with LT5, at this point in time there are many high-mileage LT5s on the road. Where is the evidence of widespread cam and lifter failures due to lower levels of EP additives in the oil? Not only are a lot LT5s high-mileage, but GF4 oils have been on the market for seven years. You'd think we have lots of LT5s with burned up cams and lifters but...we don't.

Also, the bucket tappets used in LT5s were, also, used in millions of "Quad 4" engines GM built in the late-'80s and early-'90s and a fair amount of them were still on the road in the '00s. If there was a problem with insufficient EP additives in modern engine oil, we'd have seen widespread cam and lifter failures in Quad-4s.

Bottom line: the vast majority of LT5 engines on the road (or the track) will not have problems using modern, GF-4 rated engine oils and 600-800 ppm phosphorous.

Now...you'll not above that I said "vast majority". There might a small minority of LT5s which could have a problem with lower levels of EP additives in engine oils and that's the very few LT5s which have valve spring pressures significantly higher than stock and/or aggressive camshaft profiles reground on stock cams. Significantly higher spring pressure may require a higher level of EP additives in the oil. More aggressive cam profiles reground on stock cams will result in lobes having more lift and a shorter minimum radius of curvature and that will affect the need for EP additives, as well. It is possible that an LT5 with "big" valve springs and/or reground cams will need an oil with 1000-1100 ppm phosphorous content rather than the 600-800 ppm in a GF4 rated oil. Fortunately, there are a number of oil choices with that level of phosphorous.

[scottfab]

Originally Posted by SteelBlueZR1

Regarding recommendations on engine oils and ZDP contents, if you haven't read Marc Haibec's tech paper, you should check out:
http://www.zr1specialist.com/HAT%20W...5%20Engine.pdf

I gotta go with the "hands on" guy here. Well that and the more conservative approach of staying with what was being the mantra. Until I see evidence that lowered levels of ZDP are ok I'm going to error on the side of =>1600ppm.

[xlr8nflorida]

Hib,

It's a well written article, I thought I saw the same article in Corvette Enthusiast a few years ago.

I just use the HM Mobil 1 Oil and call it a day.

Marc also agrees that the HM Mobil 1 is acceptable for the LT-5.

Too much ZDDP can cause many problems, one of which is Cat failure. Mixing any oils can change the characteristics of how they behave.

On a side note Hib, My good friend John Wysocki works on your car in Florida.

[A1990]

I use the Joe Gibbs Driven Hot Rod Oil, for the reasons mentioned throughout Hib's article and recommended by engine builder Ryan Bell, (Flyin Ryan on this forum).

[Hib Halverson]

Originally Posted by xlr8nflorida

Hib,

It's a well written article,

Thank you

I thought I saw the same article in Corvette Enthusiast a few years ago.

You saw essentially the same story in CE. The Editor gave the CAC permission to use it.

I just use the HM Mobil 1 Oil and call it a day.

Marc also agrees that the HM Mobil 1 is acceptable for the LT-5.

A good choice.

Too much ZDDP can cause many problems, one of which is Cat failure.

Catalytic convertor failure and chemical wear of the cam lobes and lifters are both problems which may occur if the phosphate concentration in the oil is too high.

On a side note Hib, My good friend John Wysocki works on your car in Florida.

My car has never been in Florida, I live in California and I do all my own service work. Maybe you have me confused with someone else?

[Hib Halverson]

Originally Posted by scottfab

I gotta go with the "hands on" guy here. Well that and the more conservative approach of staying with what was being the mantra. Until I see evidence that lowered levels of ZDP are ok I'm going to error on the side of =>1600ppm.

As much oil as that smoker of yours uses, "scottfab", you ought to be using a diesel engine oil.

All of them have lots of ZDP. I recommend Chevron Delo 400LE or Shell Rotella T. Both are available as 10W30s.

[scottfab]

Originally Posted by Hib Halverson

As much oil as that smoker of yours uses, "scottfab", you ought to be using a diesel engine oil.

All of them have lots of ZDP. I recommend Chevron Delo 400LE or Shell Rotella T. Both are available as 10W30s.

eh, as long as it keeps passing the state inspection how bad could it be?
Fortunately they don't measure at WOT up to 7k
I just love how the LT5 sound north of 6k.