# New Oil bad for Old Engines



## PhilJohnson (Dec 24, 2006)

This is something I've noticed on other forums I have been on. Apparently sometime ago the EPA decided to have oil companies lower the amount of Zddp in oil so catalytic converters wouldn't get plugged. Zddp I guess is needed to prevent excess wear on tappets and cam lobes. Newer engines use roller cams so less zddp is not an issue. I use nothing but old equipment and my daily driver (65 Ford F100) is over the hill in age. Doing a little research I found that there are oils that have the same amount of Zddp as the older standard for oil and there are additives. Unfortunately most of these oils are on the order of 5 dollars a quart and the additive can run 15 bucks. For a cheapskate like myself this is unacceptable. I buy cheapo oil from Farm and Fleet for 12 bucks for 2 gallons. I decided to email Citgo, the manufacturer of the Resolute brand of oil to find out if the cheap stuff I buy is actually hurting my engines.

This was their response which I figure may be of interest to those folks who run old stuff like myself:



> The car manufacturers notified the oil industry in the early 2000s that new exhaust emissions requirements were going to require more exhaust aftertreatment by the exhaust catalyst. These catalysts are sensitive to zinc and phosphorus contamination which reduces their effectiveness over time. Therefore, the amount of zinc dialkyldithiophosphate additive used in passenger car engine oils was reduced. This is an antiwear additive and, to compensate for its reduction, the car manufacturers modified the design of things like cam followers and lifters in new gasoline engines.
> 
> Older cars, particularly those with flat tappets will suffer higher wear with the new oils meeting the API SM Category or ILSAC GF-4 requirements. For older engines we recommend that an oil meeting the API CJ-4 Category be used. One of the requirements for this category is passing results in a Cummins engine test which measures cam, follower and crosshead wear. If an oil can pass this test, it will do an excellent job in older gasoline engines with flat tappets. Oils such as Mills Farm Rated 15W-40 Diesel Motor Oil meet the API CJ-4 requirements. These oils contain approximately 0.13 mass percent zinc which is well above the 0.08 mass percent zinc in most passenger car oils.


So from now on I guess I'll be buying the cheapo diesel Fleet Farm oil. Funny thing is the more expensive Rotella diesel oil has less Zddp that the off-brand Resolute oil. The cheap diesel oil only runs me a couple bucks more for two gallons. I have 4 gallons of cheap 10W-40 I have to use up. I think I might just mix it a little with some of the diesel oil to use it up.


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## Bearfootfarm (Jul 13, 2006)

Mobil -1 is supposed to be good too

http://www.mobiloil.com/USA-English/MotorOil/Car_Care/AskMobil/ZDDP_Levels_Classic_Cars.aspx


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## mightybooboo (Feb 10, 2004)

Interesting.


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## Beeman (Dec 29, 2002)

The reduction in the ZDDP package is true, but there are also many rumors and falsehoods out there to go along with it. No one will give you a number in PPM thast they feel is acceptable for older flat tappet engines. I have spoken to many cam manufacturers and a lot of oil and additive manufacturers. Your basic Delo,Delvac and Rotella have 1200PPM which is higher then your regular motor oils. Even Mobil 1 has reduced the ZDDP package but the high mileage oils and racing oils have a higher ZDDP count. Mobil has all of their oils on their web site and give the numbers for all of their Mobil 1's, there are many different formulations.


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## Ray (Dec 5, 2002)

very interesting return letter phil, thanks for sharing, best wishes, ray


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## unioncreek (Jun 18, 2002)

Use Mobil 1, Delo or Rotella diesel oil. They have high levels of Zinc. A lot of gas engine rebuilders will use diesel oil for start up since they are better at lubricating.

Bob


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## Beeman (Dec 29, 2002)

Mobil 1 no longer has high levels of zinc. Mobil 1 high mileage has good levels and Mobil 1 racing has high levels.

http://www.mobil.com/USA-English/MotorOil/Files/Mobil_1_Product_Guide.pdf


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## foxtrapper (Dec 23, 2003)

This is all part urban legend, old wives tale, and reality.

New engines are not universally made with roller tappets. In fact, most engines made today still use flat tappets, just like a Model T used. 

The EPA was not notified by the manufacturers, nor was anyone surprised by the changes to the standards. They had been in the works for many years.

Dig long enough and you do find information about problems with flat tappets showing up in the racing circuit some years ago. Racing engines run radical cams with steep ramps and lots of lift. This has always been hard on the tappets. Roller rockers are a good solution, but many racing bodies do not allow roller rockers or tappets. When the engine oils were reformulated a few years ago, there were lots of failures of these racing engines. Not stock engines out on the street, but radical racing engines on race tracks. Research ensued, and it was finally identified that the reduction in zinc in the latest engine oil was the culpret. Switching to diesel or motorcycle oil solved the problem.

From this, the urban legend about the massive destruction of stock flat tappet engines spawned.


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