So I have a 1955 3100 with a 235. Recently I have been reading about ZDDP additive and its use with flat tappet lifters/cam. My question is since the 235 had solid lifters with a manual transmission (which is what I have) would the ZDDP additive be useful for this engine? The one I found is the Valvoline vr1 sae 30 oil. Or does it not even matter what oil I use. Thanks
Tate

Tate, The short answer is Valvoline Racing oil still has ZDDP and one bottle of STP will treat 5 quarts of oil. For more opinions do a quick search for "zinc" at the upper right of this page and pick through the old threads that come up.
Also this VR1

Yes on the STP. I have been adding one bottle with each oil change for a few years now and have not had any problems. I use synthetic oil, 10W-30, in all of the flat tappet engines I have. Oil change at 3000 to 5000 miles.

frank

Ok cool I will look it up just needed somewhere to start and get just a bit of info. Thanks for the help

I do not recommend adding additives to fully formulated engine oils. OEM-style flat-tappet valve trains only require around 1200 ppm of phosphorus (the anti-wear component of ZDDP). You're much better off getting an oil that already has the right amount of phosphorus. The latest API CK-4 heavy duty engine oils have enough ZDDP as well as detergents to keep your engine clean.

STP is a poor way of adding ZDDP as it has less than 800 ppm of phosphorus and gooey polymers. See HAMB - STP Discussion.

See the following articles for more information:
Selection of the Right Motor Oil for the Corvair and other Engines
Engine Wear
Heavy Duty Engine Oils

Thanks for the tip. If it's on the HAMB it must be true. I'll dump my STP stock tomorrow.

I use Greased Lightening or Lucas additives in my GMC 305 V6. Truth is liked mentioned....best oils you can run are those already formulated with the right amount of zinc. I will be running Joe Gibbs Straight 30 in my 292 when I run it. But for my 305 v6 I run napa synthetic 10w-30 with greased lightening or Lucas. Been fine.

A formula is just a list of additives placed into base stock after refining. There is nothing special about zinc provided by the refiner versus zinc added to the crank case.

I find the debates over at: Bob is the Oil Guy instructive when to comes oil myths and legends.

When it comes to the need for zinc - the mid 2000s API spec simply doesn't provide enough of it. 600ppm is considered minimum for a flat tappet cam. But from what I have gleaned from research - one needs to start with 1400ppm to still have 600 parts left at the end of the oil change interval. And one needs even more zinc if the valve-spring/lifter-foot pressures are greater then stock.

One should also keep in mind why the zinc/phosphorus was 'engineered' out of the formulation in the first place - deleterious effects on catalytic converter efficiency.

Moreover, when it comes to an engine without full flow filtration - detergents are not your friend - as they are designed to suspend dirt so that it is captured by a filter. Absent a filter one needs non-detergent oil that will deposit dirt in the pan prior to it entering the sump pickup.

I will be running TSC Traveller straight 20 (mineral oil) with ZDDPplus additive. I assembled the engine using their Zpaste product on the valve train. First fire-up will take place this spring.

One more bump on this thread - CK-4/CJ-4 are diesel oil specifications - they get around the reduced ZDDP regs because such engines don't run a catalyst.

What I find most curious about this 'formulation' concept is that it appears that the additive manufacturers (Lubrizol, Rhein Chemie) appear to be doing all of the engineering whereas the oil companies are simply buying and blending in additives.

Lubrizol sells at least 7 different formulations of ZDDP:
Tri-Iso Tryline LLC whereas RC is selling less-costly substitutes based on ZINC-DI.

None of these additive packages appear to be directly available to consumers.

Detergent oil will keep your engine cleaner by keeping sludge from coating the engine. See BITOG: How does Detergents and Dispersant's work in oil?



See Selection of the Right Motor Oil for the Corvair and other Engines (Bottom Line Recommendation 10)

I agree that older engines (with filters) can use these newer diesel formulations.

But my 216 has no filter - so I don't want to pump suspended dirt through the mains and rods. I want it to fall into the pan where regular oil changes will prevent sludge build up.

A wise old man once told me "the best oil you can use in your hobby car is 'clean' oil." If you are going to change often one doesn't need to pay for 'long/extended life' formulations. Traveller SAE 20 and SAE 30 can be had for $2.5 a quart (in the two gallon jug).

They also carry a CJ-4 grade for 3 bucks a quart:
TractorSupplyCorp

When my car was running in stock trim I would fill it with SAE 20 in the late fall before the snow season. This would allow me to drive on nice dry days (in the winter) and the car would be ready to go in the spring. When summer approached (and temperatures rose) I would drain and switch to SAE 30. I suspect my service interval was between 500 and 700 miles.

Based on my research API SB (for pre-1951 engines) is nothing but mineral oil and ZDDP. An obsolete oil for an obsolete engine.

It is not clear to me how "dirt" would not become re-suspended in the oil every time the engine starts up. If the "dirt" does settle in the pan, it is also not clear to me how it would be dislodged when the oil is drained. However, to each his own.

I would suggest that you have a look at this 2004 report by the Alliance of Automobile Manufacturers. Although the report is applicable to modern engines, sludge build-up should be worse for older engines without positive crankcase ventilation systems.
Impact of Low Quality Oils on Engine Wear and Sludge Deposits

Thanks for the presentation. It is a good read. What is interesting to me is the 216 hour test that was aborted at 168 hours due to sludge build up - this is right to my point. At 60mph that's over 10,000 miles without an oil change. At 35mph it's the better part of 6000 miles.

What I struggle with in this debate is coming up with 'best' oil for a filter-less, modified, flat-tappet antique engine - as well as the proper service interval for it when installed in a hobby car.

There's an author in the UK that is an interesting read on the topic:
Car Bibles in particular the comment: "As I touched upon above, oils with a CG and higher rating typically don't contain enough ZDDP, and the replacement friction modifiers don't work in highly loaded valve trains (generally older engines especially those with 2V design). If you try to compensate by adding a ZDDP additive into a newer oil it still might not work because of interactions with other additives in the oil."

This is what has me circling back to the idea of buying an economical API SA base stock and adding just the right amount of ZDDP needed for the valve train (not to mention the anti-oxidant properties). Essentially a home blended API SB oil.

With very frequent oil changes the dirt deposited in the pan will be the first to drain off when the plug is pulled. Long before it can turn to sludge.

PS. Love your website on the Slant Six. The practical experimentation with carburetors is spot on.

And one last comment about the use of S versus C rated oils in hobby cars. The so called Service rated oils are engineered with a whole lot of 'usage' variables in mind - including short trips (with incomplete heating to less then normal operating temperatures), start-stop traffic, highway runs and an over-riding expectation that the crankcase will spend many more hours sitting with the engine off versus the hours running at optimal operating temperature - with the service interval measured by the odometer and/or a calendar. Whereas the so called Commercial rated oils are engineered around engines that are rarely shut off (delivery vehicles, cabs, cop cars, trucks etc) - with the service interval measured by an hour-meter.

A hobby car fits neither profile. But it would seem to be closer to the S than the C in terms of usage.

Good read going on here guy's.

Question, since we know that filtered oil is the way to go. Why not add a filtered circuit on the side of pan. A simple DC powered pump that sucks from pan and pushes thru a filter back into the pan?
Just a quick thought, did no research.

1) Lack of real estate (pretty tight quarters all the way around).

2) Looks. The pump and modern spin-on filter don't really belong under the hood of an early 50's era hot rod. Not to mention the hydraulic lines are kinda ugly (at least in my eyes).

3) $$ I looked at electric dry-sump pumps and peripherals for turbo oiling (over coffee this morning). One can buy a lot of oil changes for the cost . . .

Posing another view on the whole ZDDP push. For those with generous amounts of reading time. Make sure to check out the list.

https://540ratblog.wordpress.com/2013/06/20/motor-oil-wear-test-ranking/

As a matter of fact he recently updated the blog concerning oil change intervals.

That blog is a good read. His testing approach is similar to what was done in the OZ magazine Street Commodores

The problem with this 1 dimensional type testing is that it evaluates just one property - shear stability. And as you can see from the numbers in the Nightingale article the PSI estimates/calculations seem to vary based on the test apparatus. The highest value reported at rat540 is ~136,000 - the lowest ~47,000 whereas the Nightingale tests reported as high as ~295,000 and as low as ~1500 . . .

Moreover this type of testing has been placed in perspective on several forums online - including hot rod, enthusiast, and in this case an engineering site:
ENG-TIPS

The best performing oils under this kind of shear stability 'benchmark' testing would be gear-box oils - the last thing one would want to put in an engine crank-case.