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'34 Dodge 218 engine oil?


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Time for the first oil change on my watch.  Manual calls for 20wt. and I assume this should be non detergent and single viscosity.

Not much history came with car but I assume the engine has been rebuilt.  81500 on the odometer.  Runs cool, smooth, clean and (72 hp) strong

Is there a problem with using 30wt.?  Can't seem to locate any 20wt.

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Search these fora for topics on engine oil. There are many many if them - a new one about every month or so.


Do yourself and your car a favour and DO NOT USE SO-CALLED NON-DETERGENT OIL. The manual is not relevant for oil. Since then, we have developed good additive packages that will reduce wear in the engine considerably, meaning far longer life as well as help the engine run much cleaner than back then.


To learn more about oil and viscosity, read Richard Widman's paper at http://www.widman.biz/Corvair/English/Links/Oil.html

It was recognised early on that there were three problems with oils in use at the time, with five significant symptoms (source: Service Station and Motor Mechanics Manual, George George A.M.I.A.E., M.S.A.E., M.I.A.M., F.I.C., 1940, p. 87). They were exercising the minds of motor lubricant makers:
1. Corrosion by the organic acid compounds produced by the combustion of the fuel, upon the upper part of the cylinder walls and upon the piston rings.
2. Sludge formation in the oil itself.
3. Rate of viscosity reduction with temperature.
4. Extreme pressure lubricants needed for gearboxes and differentials.
5. Corrosion of the new alloys being used for bearing metal.


Additive (loosely and incorrectly called "detergent") packages include anti-oxidants that retard corrosion. They also prevent sludge build-up. And the additive packages provide for a flattening of the viscosity-temperature curve, hence multi-grade oils. The base oil is probably still S.A.E. 30, but the additives make it behave like the numbers before the W in the multi-grade designation, i.e. easier to pump at startup (e.g. 5W or 10W) leading to far less wear, and holding their viscosity at operating temperature.


Remember that back in the day, engines were full of SLUDGE (a consequence of the oil, not a design feature). It held in suspension and circulated the larger particles. With modern detergent oils, there is NO SLUDGE so the larger particles (the ones that do the damage) settle out in the sump. If you have damaging particles, your engine is already in trouble anyway. The particles that are entrained are very very small - clay sized. With non-detergent sludgy oil, there are larger bits in circulation that may be bad for the engine and they settle out when the oil slows - everywhere on stopping the engine, such as in the oil galleries in the block and crankshaft, in the dipper troughs in splash engines, in the tappet chamber, in the oil pump, in the piston ring lands, in the timing chain and so on. Once settled, it doesn't readily get picked up again by non-detergent oil. The oil ways are permanently narrowed.


I don't for one moment think they would have continued to use old fashioned non-detergent oil once detergent oil became available. Non-detergent oil would not have been readily available. Reverting to it is a retrograde step.


Note also that oil changes were very frequent. My 1930 Dodge is recommended at 1500 miles in summer and 500 miles in winter. That was how they dealt with the sludge, corrosion and oil breakdown problems: new oil, frequently. The large sumps were also to handle a lot of oil: more oil should last longer before it is all sludge. And I don't for a moment believe the mechanics would remove the sump every oil change (or second or third even) - the customer wouldn't want to wait or pay for it and it is not a fun job.


This thread is another discussion along similar lines, going at the moment.


For you, a 5W-30 would be good, CI-4 (diesel) rated to get maximum zinc. Since you know nothing about the engine, you should remove the sump and clean it out before adding new oil. Wear tests show that ANY synthetic oil is better than ALL mineral oils at minimising engine wear.


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