| [GMCnet] Oil Pressure Poll [message #366640] |
Thu, 09 September 2021 11:03  |
Oliver Moore
Messages: 21
Registered: March 2018
Karma: 1
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I have never been able to find an SAE or other research study on the
lifespan of viscosity additives. I do have experience with marine diesels.
Quite often the recommendation is for a single weight oil. Unlike over-the
road-vehicles, a marine diesel is always under a high torque load. My
experience with motorsports when I raced professionally was again for
single weight oil. I realize that is not applicable to our GMCs because
the oil was changed after practice and the race. On the subject of oil,
does anyone know if our Olds engines need ZDDP?Just a few thoughts.
Oliver
1973 Glenbrook
Patterson Stage II
Thorley Headers
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| Re: [GMCnet] Oil Pressure Poll [message #366649 is a reply to message #366640] |
Thu, 09 September 2021 17:20  |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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The beauty of true synthetics is they get the muitivis rating often because they behave that way, not because of modifiers. I know the ZDDPlus marketing guy and early on thought it was necessary. I no longer add ANYTHING to oil as most recent research shows it usually degrades the oil by upsetting the chemistry. I have never had a flat cam failure. Only GM cam failure I had was a defective roller cam. The new Hemi guys are plagued with roller cam Fails due to the roller needles failing and Stopped roller eating cam. Lifter foot pressure from big aggressive cams with big springs might require high ZDDP, but I don’t add it to engines with factory cams.
John Lebetski
Woodstock, IL
77 Eleganza II
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| [GMCnet] Re: Oil Pressure Poll [message #366653 is a reply to message #366649] |
Thu, 09 September 2021 18:57 |
Dave Stragand
Messages: 307
Registered: October 2017
Karma: 0
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For what it’s worth, around 2007 I put 75,000 miles in 2 years a 1968 Cadillac with a 472. I did have severe cam lobe rounding and lifter damage using standard oils.
At the time, the conventional wisdom was that the ZDDP additives were only needed during break-in of a new cam. Based on my experience, I feel differently and will only use ZDDP oils on any of my pre-2000 vehicles. I’ve yet to see anything that says ZDDP will HURT those vehicles (as they were designed for oil with it) so there’s that.
Lots of info and opinions out there for those who’d like to research it for themselves, so please read up on it or ask questions if you have any concerns.
-Dave
1978 Transmode near Pittsburgh
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1978 Transmode (403)
Pittsburgh, PA
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| Re: [GMCnet] Re: Oil Pressure Poll [message #366659 is a reply to message #366653] |
Thu, 09 September 2021 21:55 |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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Dave Stragand wrote on Thu, 09 September 2021 18:57For what it’s worth, around 2007 I put 75,000 miles in 2 years a 1968 Cadillac with a 472. I did have severe cam lobe rounding and lifter damage using standard oils.
At the time, the conventional wisdom was that the ZDDP additives were only needed during break-in of a new cam. Based on my experience, I feel differently and will only use ZDDP oils on any of my pre-2000 vehicles. I’ve yet to see anything that says ZDDP will HURT those vehicles (as they were designed for oil with it) so there’s that.
Lots of info and opinions out there for those who’d like to research it for themselves, so please read up on it or ask questions if you have any concerns.
-Dave
1978 Transmode near Pittsburgh
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I think it is important to note, just because in the old days ZDDP was needed in oils to assist wear characteristics, doesn’t mean that it is needed in todays oils. Oils have improved immensely over the years. Todays knowledge of chemistry and engineering have created oil blends that give us oils that far exceed the wear characteristics of yesterday’s blends. Todays blends have chemical replacement elements that duplicate the elements of ZDDP, so there may be only traces or no ZDDP in todays oils, yet have extremely high wear characteristics. So, IMO ZDDP is a nonessential element/blend unless engineered into the blend as part of the overall chemistry by chemical engineers. JWIT
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
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