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This is a perennial topic, but in researching engine oil recommendations on the internet, most people think “antique” or “classic” means a car made around 1970 or so.
My question concerns engines which do not have crankcase ventilation. I’ll presume most 1920’s Pierces fall into that category, but this applies to all real antique cars as well.
I’ve heard that fully synthetic oil such as Mobil 1 is not good in these engines because the accumulation of moisture due to no crankcase ventilation will emulsify the oil — turn it brown and frothy, ruining it in short order. Anyone know if this is true?
I’ve heard that you do not want to use a diesel engine oil like Shell Rotella because the additive packages are entirely different from what a gasoline engine requires, and can actually lead to excessive sludge formation. These oils are not blended for start-stop applications (only for long haul highway driving) and do not combat the corrosive combustion by-products of gasoline. Only diesel. Does anyone have an opinion there?
Yet Shell Rotella is one of the few readily available and cost effective oils with a higher ZDDP (zinc) additive level to protect flat-tappet engines. So on one hand, Rotella is the best, on the other hand, it’s the worst.
Yet I also recall that at one time the Rolls Royce Silver Ghost Association did a technical study of engine oil and recommended Shell Rotella across the board for Silver Ghosts. I need to find that article. . . It might be ten years ago.
We also need an oil which can withstand long periods of non-use — storage conditions. You need an oil with good “affinity” to cling to metal surfaces and combat corrosion from sitting for months.
So, can anyone speak with some authority on what modern engine oil is preferred for these earlier engines?
–Scott Dwyer
Scott,
I recently bought a 1928 Series 36 and wondered the same thing about what oil to use. I definitely am not an authority on this, but what I found through much web research is that the big controversy right now is the level of ZDDP (zinc/phosphorus) needed in oil for older engines.
The bottom line that I found is that there is much disagreement over whether modern oils are bad for older engines, specifically cam and lifter wear in flat tappet engines. Most seem to agree that in a freshly rebuilt engine, use an oil with around 1200 ppm of ZDDP for break in. Most newer “Starburst” oils are currently around 600-800ppm. Most also agree that levels of ZDDP above about 1500 ppm can harm an engine. Before the 1950’s the level of ZDDP was less than 800ppm, so our older cars ran on low ZDDP oil when new.
After reading a lot of the arguments, I am OK with modern oils in my car. The previous owner was using a modern NAPA 10-40 oil with no apparent problems. Additionally, the dual valve 6 in my car has roller tappets so the ZDDP level is not an issue.
Do a web search for “Bob Olree” (a GM engineer) and you will get a paper he did on modern oil myths. “ZDDP in oil” will get you all of the various forums and articles on whether or not modern oil is harmful in old cars. It seems that those that sell additives or specialty oils say you have to have high ZDDP. Those that sell modern oils say you don’t need higher levels of ZDDP.
There are high ZDDP specialty oils available as well as ZDDP additives if you feel uncomfortable with modern “standard” oils.
I hope this helps you. I recommend you do some research and make your own decision. I also would love to hear from other PAS members that have looked into this issue.
Dave
Scott one other thing I forgot. You mention concern about long periods of non-use. There is an additive product called “ASL Camguard”” that is specifically designed for this. I am familiar with the aircraft version for piston aircraft engines. Most aircraft mechanics are very skeptical of oil additives. Camguard has been fairly widely accepted and has not caused any problems that I have heard of. I use it in my small plane. They make an automotive version.
Dave”
Starting with Series 32 in 1921 and on to 1938, Pierce-Arrow had a system of drawing fumes from the crankcase and burning them through the intake system on the engine. This was an early type of positive crankcase ventilation. As to motor oils. The Pierce-Arrow engines run at a relatively low rpm. This was discussed with engineers at one of the large oil companies. These low rpm engines can operate just fine on regular engine oil and do not require the extra lubrication provided by ZDDP. Unless one is positive that the oil passages in an engine and particularly the crankshaft are clean and free of all sludge, do not use detergent oil. The detergent can free up the sludge and lead to plugging up the oil hole to a bearing causing it to fail. Whenever an engine is started, run it until full operating temperature is reached which should exhaust all fumes from the crankcase. Concerning storing the car say over the winter. Run (preferably drive) the car until the engine is well warmed up. Then drain and fill will fresh oil.
ANY OIL that is in an engine that has poor crankcase ventilation will develop sludge. In fact, Synthetic oils will develop much LESS sludge than normal mineral oils. Whoever made that statement about Synthetic is wildly incorrect. Oil, mixed with acids created from combustion, and condensation from the combustion of the fuel will combine to make sludge,
There is NO special feature for highway miles vs frequent start ups and short miles for an oil. The only possible consideration would be that like using a straight 50wt in your Lycoming or Continental engine in your plane, You want to assure that the oil has warmed up before significant power is needed from the engine.
Rotella is 15w-40, and would not have a significant problem with cool start ups. I use it in all my older engines, and use Mobil 1 exclusively in my Diesel trucks and tractors. Synthetic flows better at cold temps, and has better start up lubrication than most mineral oils, with the same viscosity ratings.
In your aircraft engines, many have the cam in the top of the engine, so it never gets much splash lubrication, The aircraft engines have huge crankcase breathing systems because of the engine displacement. The result is oil draining off the cam when the engine sits. It doesn’t get any drip-down oil from the crank and rods. so it gets dry, and surface rust forms from the condensation from the hot hanger/cold hanger temp cycles. and often poor drainage of the hanger floor. A rusty cam quickly chews up the flat tappets in the engines..
Our Pierce engines have cams beside the crankshaft, so it does receive pretty good splash lubrication from the crankshaft. Your engine has roller cam followers [lifters] and is less susceptible to issues with normal levels of ZDDP. There are no bad oils to use in your Series 36, but as Paul mentioned, if your engine is not fairly fresh or has always run on non-detergent, you might consider using only non detergent oil.
Personally, if you don’t know the rebuild history on the engine, I’d drop the oil pan and inspect and clean the pan, and inspect a few of the crankshaft oil galleries. most are accessible with the pan off. The galleries act like a centrifuge and spin the dirt out of the oil, leaving a thick layer in the 5/8″ diameter gallery. I’ve seen 1/2 of a gallery filled with sludge and crud.
Infrequent use of your engine is more of a moisture issue for most climates. The temperature changes and if coupled with high humidity can result in lots of condensation both inside and out. If you run you engine, never shut it down with cool oil. If you are able to do this, any accumulated condensation will have evaporated off.
The attached photo shows the crud in one connecting rod oil gallery. The main bearing galleries are normally very clean.
Most failures of camshafts and/or lifters in an engine is not due to the lack of Zinc Dialkyl Dithio Phosphate – ZDDP in the engine oil. It is failure to properly lubricate the camshaft during installation in the engine. Most new or reground camshafts come with a special lubricant. This type of product can also be purchased at a parts house. It is highly important that this be used to prevent camshaft and/or lifter failure during initial starting of the engine.