ZDDP in oil
#32
Sure wish I had some of you guys around when I was taking Organic Chemistry 101 about 52 years ago (believe it or not I did get an "A" in the course). Seriously (when am I not serious when it comes to maintaining my 928S4) I have the impression that, since my engine virtually never goes north of 4000 rpm (and I preserve my wallet by not burning rubber or driving much above the speed limit in Wyoming) I should be OK just using Mobil 1 15w-50. If there is a special additive available at one of the usual car shops or WalMart that someeone can recommend, I'll buy it.
#33
Here is the chart.
http://www.mobiloil.com/USA-English/...duct_Guide.pdf
BTW, no one has told you not to trust them.
#35
Rennlist Member
"Porsche do not recommend a diesel oil in a petrol powered engine , not last century & not in this century. Now why is that so ?
Answer = primary diesel oils are very high in detergents( compared to petrol powered oils) and these detergent packages tend to make engine oil foam too easily , so they then add silicon to reduce this tendency , but detergents attack the ZDDP , thats why primary diesel oils look as if they have very high ZDDP( new) , but as time goes by the ZDDP is damaged by the detergent packages .
Now back to the foaming , if a petrol engine from last century revs harder to make its max power as opposed to a diesel engine from last century ( like for like) this in quite normal , so in a big rig that cruises on the freeway at 1,800 RPM will give the oil way less tendency to foam as say a sports car / GT engine that is being revved to 6,500 RPM a lot .
This is where it gets interesting , foaming / air bubbles in the oil is the VERY last thing you need in a 944 / 951 or a 928 , because they have a very small flaw in their crank oil feed design , they starve no 2 con rod bearing ( 944 / 951 / 968 ) and 2& 6 con rod bearings on a 928 if the oil pressure drops to low."
"...the only thing that works is a 20w-50 ( never fails ( so long as the engine is not already badly damage by running around with a low vis oil."
I hate to be so dumb but, doesn't the above represent a contradiction? Sure, the last bit is presented in the context of high-core temp conditions; however, on the one hand I think I am being told not to use 20w50 and on the other, I have the expert's blessing???
When I look up diesel oil I find that manufacturers such as Amsoil and Valvoline say that their 20w50 is fine for both diesel and petrol engine applications. I admit that I don't find such a recommendation in my Owner's Manual; however, that is the crux of the matter isn't it? Today's diesel oil = last century's petrol oil n'est pas?
As for the foaming, I've yet to see that while running Rotella diesel oil.
Answer = primary diesel oils are very high in detergents( compared to petrol powered oils) and these detergent packages tend to make engine oil foam too easily , so they then add silicon to reduce this tendency , but detergents attack the ZDDP , thats why primary diesel oils look as if they have very high ZDDP( new) , but as time goes by the ZDDP is damaged by the detergent packages .
Now back to the foaming , if a petrol engine from last century revs harder to make its max power as opposed to a diesel engine from last century ( like for like) this in quite normal , so in a big rig that cruises on the freeway at 1,800 RPM will give the oil way less tendency to foam as say a sports car / GT engine that is being revved to 6,500 RPM a lot .
This is where it gets interesting , foaming / air bubbles in the oil is the VERY last thing you need in a 944 / 951 or a 928 , because they have a very small flaw in their crank oil feed design , they starve no 2 con rod bearing ( 944 / 951 / 968 ) and 2& 6 con rod bearings on a 928 if the oil pressure drops to low."
"...the only thing that works is a 20w-50 ( never fails ( so long as the engine is not already badly damage by running around with a low vis oil."
I hate to be so dumb but, doesn't the above represent a contradiction? Sure, the last bit is presented in the context of high-core temp conditions; however, on the one hand I think I am being told not to use 20w50 and on the other, I have the expert's blessing???
When I look up diesel oil I find that manufacturers such as Amsoil and Valvoline say that their 20w50 is fine for both diesel and petrol engine applications. I admit that I don't find such a recommendation in my Owner's Manual; however, that is the crux of the matter isn't it? Today's diesel oil = last century's petrol oil n'est pas?
As for the foaming, I've yet to see that while running Rotella diesel oil.
#36
Rennlist Member
#37
Instructor
Someone must have answered this question here
Not trying to ruffle feathers, Sean. Just looking for further education as it appears others are as well.
Not trying to ruffle feathers, Sean. Just looking for further education as it appears others are as well.
http://en.wikipedia.org/wiki/Zinc_dithiophosphate
#38
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Austin,
It is pretty simple in my book - Mobile 1 does not state what level of ZZDP it puts in its oils at any one time. They changed the level when it was known to effect the performance of a cat. They changed it back again. That is called "Flip Flopping" and I for one need something more reliable than that. There are oils out there that cost a little more but maintain the correct level of ZZDP. I chose Royal Purple because they are consistant about exactly what level of ZZDP is in the bottle.
As I only change my oil every 12 months of 15,000 miles the additional cost v the peace of mind is tiny.
I have about 16 928's and they all use Royal Purple. Apart from the one in the UK which will be changed once it reaches these shores.
I listen to real stories from people like Bruce Buchanan who has worked on more 928's than I have had hot dinners.
You pays your money you takes your choice.
Best,
Roger
It is pretty simple in my book - Mobile 1 does not state what level of ZZDP it puts in its oils at any one time. They changed the level when it was known to effect the performance of a cat. They changed it back again. That is called "Flip Flopping" and I for one need something more reliable than that. There are oils out there that cost a little more but maintain the correct level of ZZDP. I chose Royal Purple because they are consistant about exactly what level of ZZDP is in the bottle.
As I only change my oil every 12 months of 15,000 miles the additional cost v the peace of mind is tiny.
I have about 16 928's and they all use Royal Purple. Apart from the one in the UK which will be changed once it reaches these shores.
I listen to real stories from people like Bruce Buchanan who has worked on more 928's than I have had hot dinners.
You pays your money you takes your choice.
Best,
Roger
__________________
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission? George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission? George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
#39
Rennlist Member
oil and additives
I have yet to see a jug of oil that lists the ZDDP content on it. I buy at the retail auto parts stores. I have never once seen this listing on a label, no matter which store I go to. How do you know what the content is when you buy your oil (unless you special order a royal purple or amsoil or whatever). I am only talking about retail.
#41
Rennlist Member
Mobil 1 chart http://www.mobiloil.com/USA-English/...duct_Guide.pdf
I'll stick with the M-1 15-50. T
I'll stick with the M-1 15-50. T
Last edited by 77tony; 11-13-2012 at 01:38 AM.
#42
Rennlist Member
Thread Starter
whew - I was hoping this wouldn't turn into this
I was just bemoaning the lack of info on the label, making it hard to determine what brand to buy when at the auto parts store. I have read just about every oil thread over the years on this board too. there is lots of good information on this here. I use Castrol GTX 20-50 or similar, but when that isn't available, I like to know what the alternatives are, while looking at the jugs on the shelf, and not have to waste time and run home and do a research project.
I think I'm convinced that finding and sticking with a local Royal Purple rep will be the way to go. There is one that lives not too far from me.
I was just bemoaning the lack of info on the label, making it hard to determine what brand to buy when at the auto parts store. I have read just about every oil thread over the years on this board too. there is lots of good information on this here. I use Castrol GTX 20-50 or similar, but when that isn't available, I like to know what the alternatives are, while looking at the jugs on the shelf, and not have to waste time and run home and do a research project.
I think I'm convinced that finding and sticking with a local Royal Purple rep will be the way to go. There is one that lives not too far from me.
#44
Rennlist Member
Ed, rest assured that I am not participating to pick a fight. Just looking for facts. I wouldn't make this conversation about anything else. I appreciate and respect Roger for his part to keep the 928 alive and thriving.
If you are at all under the impression that my questions are muddying up your thread, I am happy to continue this conversation with Roger privately.
If you are at all under the impression that my questions are muddying up your thread, I am happy to continue this conversation with Roger privately.
#45
Rennlist Member
Thread Starter
Ed, rest assured that I am not participating to pick a fight. Just looking for facts. I wouldn't make this conversation about anything else. I appreciate and respect Roger for his part to keep the 928 alive and thriving.
If you are at all under the impression that my questions are muddying up your thread, I am happy to continue this conversation with Roger privately.
If you are at all under the impression that my questions are muddying up your thread, I am happy to continue this conversation with Roger privately.
Carry on all