This Allpar reprint of an article from Skinned Knuckles magazine presents interesting information. For example, I didn't know that two different flat-tappet engines are used in the antiwear certification tests for the new, current API-SM engine oils. The article's long, and if you just want to skip down to the stuff about ZDDP and new-oil antiwear protection in older engines, scroll down to the text surrounded by the blue box and start reading there. It'd be nice not to have to spend the money to mess with EOS or other additives, eh?

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Dan,you ROCK

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83 B-150 slant 6,4 speed. 79 B-300 360 pathfinder 4x4. 74 W-300 318 4x4 git-r-done 80 B-100 sl6,4speed

How much faith do you put in adequate? I wonder what the BITOG additive zealots have to say about this.

I think it's encouraging that the modern oils are still tested on engines with flat tappet cams. My flat tappet engines all get Delo 400 in 15W-40 and the Intrepid gets Valvoline or Castrol 10W-30. For cam break-in I'm still going to use GM EOS or similar, but flat tappet cam break-in is a special case.

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Joshua

I've trusted modern technology to take care of things like effective lubrication in my old engine, but the article made me realize that those of us with ancient vehicles are no longer the focus of their studies.

Last week, I took my rebuilt '73, 318 truck into the Dodge dealer for an oil change. I didn't specify which oil to use, and they didn't ask. They installed 5W-30 Mopar oil, but I have no idea if it will properly lubricate my engine. I've always used 10W-40 Pennzoil in my older vehicles when I did the work, but I'm getting to that age where I find it easier to have the dealer do it.

I'm curious what the rest of you have been doing, and what you intend to do after reading the article.

I would not run 10w40 in anything; it is a particularly problematic (sludge-prone) grade because of the relatively high level of viscosity modifiers needed to cover that particular spread of cold vs. hot viscosity. With a rebuild '73 318, I might've picked 10w30, but I definitely don't think 5w30's going to make any problem at all...though you must have one exceptional Dodge dealer! Most auto dealers give such poor value and low competence in the service department, at least on cars older than about 5 years, that once the warranty expires there's no good reason to patronise them.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I've been pleased with the service at every dealer here in Texas...which is more than I can say for Washington state.

I moved from the DFW area 6 months ago, and was worried that I'd lose the good service, but the local dealers are also excellent. To top it off, an oil change and filter is only $14.99, if you make an appointment, and $19.99 if you walk in. It cost me $21 because the truck uses 6 quarts, but that's $11 cheaper than the quick change places charge around here.

I was getting sort of upset because it took nearly an hour to change oil, but when the tech brought it up front, he apologized. He said the ticket hadn't stated I was waiting for it, and they kept the truck back in the service bay for a while so all the mechanics could get a look at it. Apparently they don't get to see many clean old Dodge trucks.

Hmmmm... thats funny (I'm not doubting about the chemicals, modifiers, etc) about not using 10-W-40 in anything.... quite the opposite I use it in everything! I remember hearing the word around town was that GM was voiding warranties on engine issues if they could prove that 10-W-40 was run in their cars similar to what you say about sludge. BUT the guys in-the -know at the time had said that 10-W-30 had even more of the "bad" additive in it than 10-W-40 did so I stayed with the '40. No worry for me, because I have never owned a vehicle new enuf to even HAVE a warranty on it. I have never had a sludge issue myself,that wasn't created by previous owners.I think that it has to do more with brands and how often the oil and filter get changed (I NEVER believed in the filter-every-OTHER-oil change idea as listed in many of the glovebox owners manuals I have had) and the brands that are chosen than simply just the weight that is chosen. Granted though, the weight chosen can play into how fast a cold engine gets oil flow but that's a different matter. For the 1st time in years I changed from the 10-W-40 the last oil change on my tired ol' truck, in favor of 15-W-40 Rotella just as an experiment. (NO, it isn't diesel)
I have noticed that it takes a sec longer for the mechanical gauge to move than the 10-W-40 but no rattles on startup (neither with the 10-W-40) but it carries much higher oil pressure across the board; cold, hot, idle, cruise, everywhere.

All the manufucturers started specifying 10W30 rather than 10W40 a few years ago for a simple reason. The lower viscosity meant reduced drag on the internal moving parts of the engine. Less drag mean better fuel economy at a time when they were all struggling to meet CAFE requirements. In a typical automotive engine carefully operated and maintained there is no need for the additional viscosity of 10W40 and the engine will deliver more power and better economy with the lighter weight lubricant.

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David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

That has never been the case.
No, that's definitely a significant determinant of how much sludge you'll wind up with, but this particular phenomenon has to do with how much VI modifier chemistry (basically liquid polymer) is in the oil vs. how much oil is in the oil.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I use and will continue to use 10W-40 oil. I've never had a problem with sludge, though my long commute of 80+ miles a day helps I'm sure. Plus, no rod knocks, 145 to 150 psi compression, and 45-50psi oil pressure dosn't lie.

That article is a bit out of date. The curent diesel oil is CJ-4 it doesn't have ZDDP, only the older CI-4 has it & it is getting hard to find. GM EOS has been reformulated & the ZDDP is gone also, as has the red bottle STP 4 cyl formula. There has been a problem with some high spring pressure V8s with flat tappet cams losing the cams, maybe bad oil, maybe bad cams. You might look at www.zddplus.com

It's from one year ago.
The question at hand is whether ZDDP per se is necessary, or if newer EP additives effectively replace it. The inclusion of two different flat-tappet engines in the SM certification tests suggests the answer is yes, but I am still keeping an open mind for good, properly sourced information one way or the other.
Please cite your source for this info. If it's true, then it would tend to indicate that substances other than ZDDP can get the job done!
Source...?
Not a reliable source for unbiased info — they've got a strong financial interest in the answer being "no, you don't get adequate protection unless you buy our gookum".

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

If "a few years" means more like 25 years...
While that is an argument in favor if 10w30, that's not the reason for the switch. General Motors occasionally does something right, and one of the things they did right around 1980 was a very thorough study on oil behavior. They found that 10w40 was the nastiest of all in terms of its propensity to form both sludge and combustion chamber deposits. Because it had to start with a light base oil to get the "10" end of things when cold, it had to use a ton of friction-modifying polymers to get the "40" when it gets hot. 20w50 actually used far less polymer additives because it started with a heavier base stock oil

Now, a lot of this is moot with modern synthetic oils that get remarkable viscosity ranges with fewer polymers (Mobil 1 10w30 has used NO friction modifiers for at least 12-15 years now, and even their 0w30 probably has fewer modifiers than a 1980 10w30.) But one thing has never changed- of all the common grades, 10w40 is going to need more modifiers than just about anything else, so its still the "worst" pick. That's why the few applications that really do need a heavier oil tend to specify either 15w40 (a common synthetic Diesel oil grade) or 20w50.

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There used to be a very good write-up on Crane Cams' website which detailed some issues they had been seeing. Crane's always been on my list of "they seem to base everything they sell on a Chevy grind" companies, but the article was interesting in that it cited several possibilities for the rash of failures they had seen, INCLUDING poor materials in the lifters they had been supplying. They admitted that several things had happened at once, but they couldn't rule out reduced ZDDP at that time. The only article I could find on their site just now (I only did a quick search) basically says 'use our zinc additive for BREAK IN (my emphasis) and use racing oils if appropriate for your application.' So they may be backing off a little.

At least one cam manufacturer had also started drilling a small oil hole in the lifter face itself to provide direct pressure lubrication for each cam lobe and felt that this change would alleviate the need for so much extreme pressure additive.

Personally, I'll wait a while and keep using diesel engine oil just to be safe. As long as your engine isn't an oil burner, diesel oils shouldn't be a problem. If it DOES burn oil, then you may have a problem with combustion chamber deposits and detonation because it is not as low-ash as gasoline oils are.

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