Beware of engine oils for our older technology Engines
Compiled by Steve K.
20th October 2010
This information is a compilation of findings while investigating the most suitable engine oil to use in older motor vehicle engines that have flat tappet technology for valve operation.
The information contained on this page is to help motor hobbyists understand the technology of lubricating oils and their impact when used in our old technology engines. You are expected to research information to determine what is most suitable for your requirements.
This investigation was triggered when Scott R. broached the subject at our September 2010 General Meeting.
A Bit of Background
These excerpts referenced from "Old Cars Weekly".
"June 23, 2009, by William C. “Bill” Anderson, P.E.
There were few choices when the 1959 DeSoto Firedome rolled
off the assembly line.
little about ZDP
What does it all mean?
It means that modern oils made for modern engines will probably harm our older engines.
What do we do?
We should be using oils and/or additives with sufficient levels of Zinc (Zn, ZDDP/ZDDZ) and Phosphorus (P) to protect our engines. We need 1200~1400ppm (parts per million). Too much is also harmful.
There are oils designed for various purposes that could be used.
Oils designed for internal (spark) combustion engines with API codes of "SH" and "SJ" have (at the time of writing) sufficient levels of Zn & P to protect our engines.
Oils designed for diesel engines with API codes of "CJ-4" and "CI-4" also have (at the time of writing) sufficient levels of Zn & P to protect our engines.
CAUTION: Oils designed for use in diesel engines contain detergent, and are, in part, designed to remove sludge and keep the internals clean. The use of diesel oil in an engine that has not recently been overhauled may cause serious problems in that the detergent will likely loosen any sludge build up inside the engine allowing it to travel around with the oil and potentially block oil ways, resulting in bearing failure.
It is recommended that diesel oils only be used in an engine that has just been overhauled, and/or that is known to be clean and free of any oily build up in the engine. If detergent oils are used in an old engine containing sludge and other deposits, the detergent action is likely to loosen the sludge/build up allowing to be circulated through the engine which could cause blockages in oil ways, leading to damaged bearings.
The detergent also has the effect of removing the anti-wear films coatings, so low detergent would be better. Nowhere on the label should the oil say 'for emission system protection' or 'for use in engines equipped with particulate emissions filters'.
This information referenced from LN Engineering website.
The current API standard is SM, and calls for 0.06-0.08% Zn and P.
As can be seen in the above table, the latest API code of SM does not have enough Zn & P to suit our engines, while CJ-4 and SL are a bit light on for Phosphorus.
Vehicles fitted with catalytic converters should note use engine oils with high levels of Zn & P.
This is not a complete list, and if you identify other suitable oils, please advise our webmaster so they may be added.
What can we use in Australia?
At the time of writing, there are a few locally available oils that are rated with the above codes;
Castrol GTX 20W/50, API SJ
Castrol XL 20W/50, API SJ (From label on bottle. Unable to locate data sheet)
Penrite: SHELSLEY MEDIUM, Vehicles 1920 to 1952
Penrite: CLASSIC MEDIUM, Vehicles 1953 to 1966
Shell Helix HX3 20W/50, API SJ/CF
Lucas Heavy Duty Oil Stabilizer < to be confirmed
SLICK® 50 < to be confirmed
If you are interested in reading more on the American Petroleum Institute (API)
"Engine Oil Licensing and Certification System" click >here< to open their PDF file, in a new window.
Information presented here is a suggestion only, and not necessarily intended to be the correct or only way to carry out a repair.
If you choose to use this information, you do so at your own risk
The SCCNSW, and/or it's members, will not be held accountable for problems that may occur as a result of using this information.
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