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Oil for your Studebaker Engine

Published in Technical
Written by  22 November 2012
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For over two years our GT Hawk has been off the road due to a tired engine. After $2500 in parts, machine work and with much assistance from Bill Patterson, the GT Hawk will be out on the road in 2008 with a superbly rebuild 289. I was talking to Bill the other day and he indicated that we should start looking for oil for the newly rebuild engine and I asked what he meant. Well to my great surprise proper oil for our Studebakers is getting very scarce with the news that the new standard for oil is “SM” which has completely eliminated the additive “ZDDP” (zinc dialkyl dithio phosphate). This additive has been present in oil for over 70 years in various content levels and greatly assists in the proper lubrication of camshafts and flat-top lifters in older stock engines (pre-1988) cars or trucks.

I have done much research on this subject and many on the internet have a lot of concern that that the oil companies have eliminated this additive. In 2007, they have removed ZDDP in most of our motor oils to meet new emission standards, while being no longer needed in modern engines and also ensures longer life for your catalytic converter. Without this “ZDDP” additive your camshaft and lifters in such cars as Studebakers, AMCs and many other similarly designed engines could prematurely wear out and will have to be replaced much sooner then necessary. Many antique or vintage car owners have different solutions for this problem but being in Canada does create some problems with the quick availability of any suitable additives or oil. Many major oil companies are still doing “research” on this problem which does little for us if our camshafts are prematurely wearing out.

So what do we do for the next oil change? Ensure to check the oil and don’t use “SM” standard or Energy Conserving oil unless supplemented with some ZDDP additive. On the market is an additive called “ZDDPlus” which is available on the internet at or at such Auto flea markets as York or Reidsville. I have just purchased six bottles at around $10 US per bottle. One 4 oz bottle mixed with any suitable oil which includes the “SM” grade will help ensure that your camshaft and lifters are properly lubricated. If you can track down some 4 Stroke motorcycle oil rated at “SG” or Diesel oil which is Heavy Duty rated such as straight 30 or 40 SAE oil then it should be suitable. Check the product label or their company website and the applicable product data sheet to see the Zinc or phosphorus content in the oil. If you have oil in your garage then see if it is in the “SH” to “SL” grade ranges which can still be used in our Studebakers with varied levels of success. Also some older bottles of STP oil Treatment or GM EOS reassembly oil have ZDDP in it. For myself, the best bet was to
get afew bottles of the ZDDPlus additive and let’s hope that the oil or additive companies can come up with readily available, alternative solutions to keep our Studebaker engines
properly lubricated and on the road for many years to come.

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