oil again

[William F.]

Re: oil again

Duke,
Can you just tell me if the tests you reference show that an adequate amount of ZDDP is necessary to prevent wear of flat tappet cams and lifters? Conversely does it show failure of sliding friction components if a modern oil with low ZDDP is used? I just want to have some reason to refute the "ZDDP is a Myth" article based on facts rather than anecdotal evidence or just opinion. I know what some cam manufactures say but some others say some of the com/lifter failures in the past were really due to poor quality parts. Ever any recommendations from oil companies or Chevy service bulletins, etc?
Thanks
Thanks

[Steve G.]

Re: oil again

New camshaft failure at startup is an issue that has been in existence for at least 40 years (that's when I joined the industry, but I'm relatively sure it didn't crop up just when I started). It was prevalent enough at that time that camshaft manufacturers included a warning note in the camshaft packaging that, just like today, you use their special camshaft lube on the cam and lifters when assembling and follow a strict break-in procedure of not allowing engine rpm to drop below 2000 rpm for the first 20 mins of operation. Failure to do so would result in significantly reduced camshaft life, if not immediate failure. I'm sure there were engine oil recommendations as well, but I don't remember them. This was long, long before anyone ever dreamed of dropping zinc.

Now, when this same failure happens today it is the fault of present day oils, in spite of the conflicting theories and unanswered questions.

Why does it only happen on some engines and not all on others?
How does the oil industry claim 40 years of unbroken backwards compatibility through the oil classifications? Why no disclaimer of incompatibility with flat tappet engines? Liability?
Why are the manufacturers of flat tappet engines sold today in the Ag, Industrial, Commercial, home and garden markets not requiring the use of CJ-4 diesel oil or zinc additives in their products?
Why did we have separate classifications for gas and diesel engine oils back in the day when virtually all gas engines were flat tappet? Yet, whatever that reason in 1970 it is no longer valid today?
Proponents of the lost zinc theory would have us believe that the difference between today's roller engines and the flat tappets is one rolls over the lobe and the other slides over it. But, as was pointed out earlier, the lobe to flat lifter contact is a very narrow margin on the one side of the lobe contacting the lifter well away from it's centre, causing the lifter to rotate. The lifter actually rolls over the lobe. Break-in procedures ensure the start of that rotation. Those that have floor time in a shop and have seen higher mileage worn engines know that when the lifter face and the cam lobe wear to the point that the lifter stops rotating, the remaining life of the lobe is measured in minutes.
There has been no evidence of increased wear in todays engine where there is still a sliding contact, specifically helical oil pump drive gears.

A healthy dose of skepticism is is a good idea when taking your information from the internet. Remember the fuel perc myth.

[Duke W.]

Re: oil again

I don't have any test results, but blenders of both S and C-category oils add ZDDP to near the respective P limits. If it wasn't necessary to pass the wear tests, it wouldn't be added.

As far as refuting the "ZDDP is a myth" theory, why bother wasting your time. It's one amateur going against the entire automotive and petroleum industries and their 100 or so years of experience blending engine oil to promote maximum engine life. Get serious!

lobe-lifter failures are rare as long as OE or OE-equivalent components are used, which are Parkerized to aid break-in. Aftermarket manufacturers like Comp Cams don't Parkerize their cams, and this in combination with more aggressive than OE lobe dynamics causes very high failure rates for their flat tappet cams compared to OE equivalent.

All Federal Mogul and Dana Corp. OE equivalent cams are Parkerized, and they are my first choice. Crane Parkerizes their cams, too, so they are my second choice for OE equivalent and first choice for custom designs.

Duke

[Dick W.]

Re: oil again

Why did we have separate classifications for gas and diesel engine oils back in the day when virtually all gas engines were flat tappet? Yet, whatever that reason in 1970 it is no longer valid today?

The diesel oils of the early 1970's were MIL Spec 2104-B. You could use them in gasoline engines with excellent results but not the other way around. We ran ONE motor oil back then, Texaco URSA, in over 2,500 vehicles with many gasoline engines going over 200k. Seldom did we replace a gas engine before the vehicle was traded. We did have two different manufacturers of HD gas engines that had problems but not related to oil. One was valve seat inserts coming out of the heads and the other was burning pistons due to miscalibration of early emission standard fuel delivery and spark timing curves.

[William F.]

Re: oil again

Well, I'm going to continue to use Rotella T oil, mainly because a reliable source, the EXXON oil engineer stated in the 1999 Car and Driver article I previously referenced, that diesel oils give better corrosion protection in our infrequently driven collector cars. The ZDDP won't hurt, but no one in this forum has provided other than anecdotal or "because it used to be there but isn't any more" evidence, such as recommendation for an oil industry engineer or tech bulletin from oil or vehicle companies that ZDDP provides more wear protection from sliding friction that the antiwear packages in "S" type oils. Maybe we ought to consider the findings of the 540 rat blog guy's tests.?

[Steve G.]

Re: oil again

Of course everyone should use the oil they like in their car.

I'm more inclined to follow the recommendations of the API. It is the standard agreed to and followed by the engine manufacturers. It is the result of collaborative efforts between the petro-chemical engineers and the engine manufacturers. I would take that as being far from anecdotal. If you look to their table of C and S classifications you will find plenty of CAUTIONS about incompatibilities with engines moving forward, but none backwards. I'll bet my engine that wasn't an omission or an oversight. Nowhere in the C classifications will you find a recommendation for use in flat tappet gas engine. Again, I don't think that was an oversight.

Would I trust the blog guy's test results over those of the engine manufacturer's and chemical engineer's, over the cummulative knowledge from 100 years of following engines and oils? Tough sell.

[Joe L.]

Re: oil again

Of course everyone should use the oil they like in their car.

I'm more inclined to follow the recommendations of the API. It is the standard agreed to and followed by the engine manufacturers. It is the result of collaborative efforts between the petro-chemical engineers and the engine manufacturers. I would take that as being far from anecdotal. If you look to their table of C and S classifications you will find plenty of CAUTIONS about incompatibilities with engines moving forward, but none backwards. I'll bet my engine that wasn't an omission or an oversight. Nowhere in the C classifications will you find a recommendation for use in flat tappet gas engine. Again, I don't think that was an oversight.

Would I trust the blog guy's test results over those of the engine manufacturer's and chemical engineer's, over the cummulative knowledge from 100 years of following engines and oils? Tough sell.

Steve------


The Shell Rotella and Chevron Delo that I mentioned are dual-rated for both "C" and "S". If a "C"rated oil was not also "S" rated, I would not use or recommend its use in a gasoline engine.

[William F.]

Re: oil again

Steve et al
I was being somewhat tongue in cheek about giving a lot of credence to "rat540" oil test blog. Just wanted to smoke out evidence or lack thereof of need for the higher levels of ZDDP found in diesel oils compared to S only rated oils. As noted, I do believe the added corrosion protection afforded by Rotell T, etc is a good reason to use these oils in our older collector cars.