Oil additive question
Thread Starter
Instructor
Joined: Feb 2006
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From: Santa Barbara California
Oil additive question
I have an 80 with a rebuilt 350 with approx 4000 miles. The local owner of a classic car shop and brake and wheel store suggested I run 10/40 instead of 10/30 and also add a bottle of GM assembly oil every time I change oil for engines like mine that have flat tappets. I haven't added this yet as it says on the bottle that it is not to be used as an additive. Has anyone heard of doing this? He said the block was an older one. Thanks for any input, Jay
Melting Slicks
Joined: Jul 2004
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From: Maryland
You should use GM EOS and CI-4 rated oil as a break in mixture only. Change the filter the first 30 minutes of break in but leave the oil mixture in and change it and the filter in 500 miles. Use API CI-4 oil such as Chevon Delo 400 thereafter as CI-4 has the highest amount of ZDDP an anti wear additive. EOS should not be used as a regular additive thereafter as it is not an ashless substance and can lead
to internal engine coking.
to internal engine coking.
Last edited by Donald #31176; Sep 11, 2007 at 12:29 PM.
Thread Starter
Instructor
Joined: Feb 2006
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From: Santa Barbara California
Thanks Donald for your help!! Could you tell me what zddp is? I hope that when the engine was rebuilt that the GM assembly fluid was used. Should I stay with 10-30 here in California or 10-40? It doesn't seem like it would matter much to me. Thanks again, Jay
Le Mans Master
Joined: Mar 2004
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From: Little Rock AR
The EOS is probably not good for a catalytic converter. If you are running a cat you might want to keep that in mind.
BTW - If you have any of the GM Engine Oil Suppliment, save it for a new cam break-in. They have discontinued it.
There is a simmilar product sold by AC Delco but I do not know for certain if it is as good as the original stuff sold by GM.
-Mark.
BTW - If you have any of the GM Engine Oil Suppliment, save it for a new cam break-in. They have discontinued it.
There is a simmilar product sold by AC Delco but I do not know for certain if it is as good as the original stuff sold by GM.
-Mark.
Thread Starter
Instructor
Joined: Feb 2006
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From: Santa Barbara California
Thanks for the advice Mark, I will hang on to that GM Assembly lube, thanks again for the help. I purchased it from an independent and had been told I could get more from GM. Jay
Melting Slicks
Joined: Jul 2004
Posts: 2,862
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From: Maryland
ZDDP is a zinc phosphate compound in motor oil that is necessary to prevent premature cam wear. Within the past 3 years oil marketeers have reduced the amount of ZDDP in response to the newer cars as ZDDP will degrade the emission sensors . Newer cars use roller type valve train systems and do not need the higher ZDDP concentration. For vintage engines of flat tappet design use API rated CI-4 or CJ-4 oil. CI-4 has about 1200 parts/million of phosphate the anti wear component of ZDDP. The newer SM rated oil is limited to 750 parts/million and the "energy saving " SM rated oils are even less. The viscosity you chose is dependent on the lowest anticipated starting and operating temperature. Most CI-4 oil sold is 15w-45 which is OK for starting temperatures down to 15* F. and operating temperatures of over 100* F.
Thread Starter
Instructor
Joined: Feb 2006
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From: Santa Barbara California
Thanks Donald for the Great info on zinc phosphate. I just did an oil change awhile ago, but will definately switch over soon. One more question Donald, I went to the Chevron website to learn more about Delo 400. According to the C classification the oil you reccomend is for diesel engines. I am not familiar with the difference between gas engine oil and diesel and was wondering if it is ok to use this oil in a gas engine? Thanks Jay
Last edited by manzanman; Sep 11, 2007 at 09:54 AM. Reason: need more info from Donald
Melting Slicks
Joined: Jul 2004
Posts: 2,862
Likes: 195
From: Maryland
Thanks Donald for the Great info on zinc phosphate. I just did an oil change awhile ago, but will definately switch over soon. One more question Donald, I went to the Chevron website to learn more about Delo 400. According to the C classification the oil you reccomend is for diesel engines. I am not familiar with the difference between gas engine oil and diesel and was wondering if it is ok to use this oil in a gas engine? Thanks Jay
Delo 400 "exceeds warranty requirements for all gasoline,diesel and turbo charged engines specifying this SAE grade and API service classification."
When choosing oil for vintage flat tappet engines CI-4 or CJ-4 oils have the highest ZDDP concentration and that is what you want.
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