Engine Oil Information Compilation

[jmettee]

I've been wanting to do some updated researching of engine oils for use in the DMC. Lots of info & mis-info/wives tales & the like on the internet. It makes it hard to be confident of anything. Bottom line, I've been using Mobil 1 15W50 with great results but I'm thinking of trying Shell Rotella T 15W40 or Chevron Delo 15W40 (both are rated for diesel use & are heavy duty oils). Since I took the time to research the information, I thought it would be good to share it here for others to benefit from a single source of info.

Basics: the DMC manual calls for 10W-30, 10W-40, 15W-40, 20W-40, for my weather conditions (southern PA) & 20W50 for weather over 64F. Of those, I understand the 10Ws are not recommended because they are a bit light at startup. I tried 10W30 Mobil 1 one season & the engine was noisier until it warmed up.

DMCH recommends Castrol GTX (conventional) 20W-50. I believe Dave Swingle at DMC Midwest likes Mobil 1 15W-50 (full synthetic) which is what I have pretty much always used since I got mine in 2008. My engine has been spotless when I've been inside it, so I know it keeps things clean.

The big argument is that we have a flat-tappet design for our valve lifters & it's metal on metal wear. Many think that we need ZDDP (Google it) levels of 1000ppm or higher. These 3 links provide decent detail in a brief read.

http://jalopnik.com/pat-goss-debunks-zinc-in-your-oil-1443647531 (watch the video)
https://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=111622
http://www.opelclub.com/ZDDP2.pdf


Then there are these 2 posts of overlapping data of a guy doing independent testing showing the actual zinc & phosphorous levels as well as a wear pressure rating. Of the oils discussed, they rank in this order from highest wear pressure protection to lowest. All are good, but you can see the differences. I pulled out the commonly available oils from the list that are also in the DMC owners manual (excluding the 10W oils). Notice that the 4 conventional oil have better wear pressure than the synthetic Mobil 1. DMCH's recommendation appears to have the best pressure wear rating & the 3 popular diesel oils are very similar. I find it surprising that the Mobil 1 full synthetic is the lowest of the group, but I still consider it a great choice.

20W50 Castrol GTX conventional, API SN = 96,514 psi
15W40 CHEVRON DELO 400LE, conventional, “Load Carrying Capacity/Film Strength” = 73,520 psi
15W40 MOBIL DELVAC 1300 SUPER conventional, API CJ-4, CI-4 Plus, CI-4, CH-4/SM, SL = 73,300 psi
15W40 SHELL ROTELLA T conventional, API CJ-4, CI-4 Plus, CH-4, CF-4,CF/SM = 72,022 psi
15W50 Mobil 1, API SN = 70,235 psi


http://www.chevelles.com/forums/18-engine/391711-high-zddp-oil-anyone-try-thoughts.html
http://www.sccoa.com/forums/showthread.php?136304-What-oil-brands-offer-the-best-protection-***Good-read*** (Same list as above, but filtered to only list oils with ZDDP levels of 1100 or higher)


Here is some more if you want to dig deeper at some of the better information I found when searching.

https://www.motorists.org/blog/warning-if-you-have-an-older-vehicle-choose-your-oil-carefully/
https://mobiloil.com/en/faq/ask-our-auto-experts/questions-for-auto-experts/mixing-motor-oil-to-reach-the-right-zddp-level-for-classic-cars
https://mobiloil.com/~/media/amer/us/pvl/files/pdfs/mobil-1-oil-product-specs-guide.pdf
https://www.hemmings.com/blog/2012/10/18/tech-101-zinc-in-oil-and-its-effects-on-older-engines/
http://www.corvetteforum.com/forums/c3-tech-performance/2484100-list-of-flat-tappet-oils.html

[Chris 16409]

I have been using the Shell Rotella T Oil for the last couple oil changes. The Shell along with the Chevron Delo are two of the brands that Rob Grady has been recommending.

[Mark D]

Great information, thanks for condensing it all down for us. In regards to this testing:

http://www.sccoa.com/forums/showthread.php?136304-What-oil-brands-offer-the-best-protection-***Good-read***

My last oil change was with Valvoline VR1 20W50 after having read the oil threads here and on DMCToday. That oil wasn't one of the oils tested, but the 10W30 was and came in ranked at #3:

3. 10W30 Valvoline VR1 Conventional Racing Oil (silver bottle) = 103,505 psi
zinc = 1472 ppm
phos = 1544 ppm
ZDDP = 1500 ppm

I wonder if the results for the heavier weight oil would be similar? I know the ZDDP levels are the same across the various weights, but I was kind of disappointed not to see the Load Carrying Capacity listed for the 20W50.

[jmettee]

Great information, thanks for condensing it all down for us. In regards to this testing:

http://www.sccoa.com/forums/showthread.php?136304-What-oil-brands-offer-the-best-protection-***Good-read***

My last oil change was with Valvoline VR1 20W50 after having read the oil threads here and on DMCToday. That oil wasn't one of the oils tested, but the 10W30 was and came in ranked at #3:

3. 10W30 Valvoline VR1 Conventional Racing Oil (silver bottle) = 103,505 psi
zinc = 1472 ppm
phos = 1544 ppm
ZDDP = 1500 ppm

I wonder if the results for the heavier weight oil would be similar? I know the ZDDP levels are the same across the various weights, but I was kind of disappointed not to see the Load Carrying Capacity listed for the 20W50.

Not sure, for Mobil 1 it's a bit counterintuitive for me based on ZDDP & actual wear pressure. From the other list I referenced:

3. 5W30 Mobil 1, API SN = 105,875 psi
zinc = 801 ppm
phos = 842 ppm
moly = 112 ppm

22. 5W20 Mobil 1, API SN = 94,663 psi
zinc = 764 ppm
phos = 698 ppm
moly = 76 ppm

52. 15W50 Mobil 1, API SN = 70,235 psi
zinc = 1,133 ppm
phos = 1,168 ppm
moly = 83 ppm

[opethmike]

I use peanut oil in mine. Works great, and smells nice.

[DMC-81]

I use peanut oil in mine. Works great, and smells nice.

:hysterical:

[mr_maxime]

I also use vr1 20w50 since I keep finding it for $1-2/qt on clearance. Just makes it a no brainer for me at that price.

[vwdmc16]

Also a VR1 20w50 user, but it seems its no longer available in CA, that much zinc will destroy the earth or something. .....


So time to find something new.

[mr_maxime]

Also a VR1 20w50 user, but it seems its no longer available in CA, that much zinc will destroy the earth or something. .....


So time to find something new.

It's possible that your local parts store may not have it. I bought it on clearance at advance auto cause they were discontinuing it and after trying to buy all locally available ones, I found out it's store based. For some odd reason though, the only store I bought out reordered it, priced it normal, then put it back on clearance.