Old cars, synthetic oil

[AK260]

going to change my oil soon, 2500 miles on VR1. Plan to use rotella T4 15-40 unless someone yells "DONT DO IT DAVE" my thinking on this is the T4 may have a better detergent package to help clean up carbon deposits that may be in my 100k+ engine. I have been using the VR1 for about 25k miles again avg about 3k between changes.

What I’ve read suggests we shouldn’t use diesel oils as the formulation is for a different environment and soot content etc.

I guess any modern motor oil is better than what was available when out cars were born, but the question I would ask is do you know if it has ZDDP?

In fact there is a debate raging in classic car circles about do you really need ZDDP as modern oils cling so much better and have good sheer resistance.

I’m not sure I know enough to have an opinion though.

[Zed Head]

The specs look pretty good.  I seem to remember that there used to be a warning on the container about the ZDDP content and catalytic converters.  But I don't see it anymore.  The Rotella is a low soot, low sludge formulation.  Both sound good.  Maybe they got rid of the ZDDP finally.

I used regular motor oil, no ZDDP, in my two L28's and did not destroy any cams.  I think that the ZDDP is more for break-in than long-term usage.  Not even sure it's a huge issue with catalytic converters either, I think it's a long-term degradation of the converter if you keep using it, and if your engine burns oil.  How did they used to break in a 280ZX engine or California 280Z engine and what did they run afterward?

Always a fun discussion topic.

https://rotella.shell.com/en_us/products/conventional-motor-oil/rotella-triple-protection.html

https://rotella.shell.com/en_us/products/conventional-motor-oil/rotella-triple-protection/_jcr_content/par/productDetails.stream/1520976123954/02cdc4507e718cd0fc768d05faab7059e52f0938/t4-15w-40.pdf

https://cen.acs.org/articles/84/i31/ZDDP-motor-oil.html#:~:text=ZDDP operates by forming a,tailpipe of an operating engine.

[Dave WM]

I think the plan will be as follows

drain oil, keep a sample of the 2500 mile VR1

run the rotella for 1000 miles, drain keep a sample compare how dirty it looks to the 2500 mile VR1

Refill with VR1.