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brindo wrote: ↑Thu Feb 01, 2024 4:31 pm My understanding is that semi and full synthetic oils are more susceptible than a mineral oil to cracking as they get hot, but I don’t know at what temp that actually is. Certainly any oil cooling the underside of the pistons would be a lot hotter than 100 degs C.
I am not a chemist, but I guess depending on where they crack could either turn into diesel or grease – either one will cause an engine failure.

My only experience of it was oil down valve guides forming a varnish which led to valves sticking.

Gareth wrote: ↑Thu Feb 01, 2024 4:37 pm IMG_2160.jpeg
IMG_2162.jpeg

I think I’ll add a trough here

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And I’ll add suction outlets here and here

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Any thoughts?

vlad01 wrote: ↑Thu Feb 01, 2024 5:13 pm Yeah, I don't know what that post was on about. Very much a case of anecdotal based on one dubious data point. There is zero reason for mineral other than budget constraints.

I switched from mineral to full syn long ago and only use mineral if I can't get the grade I want in syn. I have issues with 20W50 mineral, more so the viscosity than the oil base. But I use 10w50 full syn for the V6 and have so for almost a decade and a half and one engine that I actually got to see the wear and tear from near new to high ks was very little wear, certainly less than the ks would have suggested. The engine was also spotless inside, bare silver metal in most places and light yellow tanning in other areas. It had a good service interval though, but modern syn oils have less tendency to break down and form long chain compounds that form tars and what not during various chemical reactions.

The few issues I found was with the mineral was oil pressure was crazy high when cold and worrisomely so in winter. Then when fully warmed in hot summer I found lifters can get bleed down and tick even when pressure was fine.

Syn is more stable with the 2 ends of the temp range.

lastly, oil leaks and oil consumption! mineral is significantly worse than syn in my testing. I attribute this to mineral breaking down with use and heat and the molecules cracking to smaller compounds and these find their way out in microscopic gaps. Used mineral oil feels watery when it's due for service when warm and like honey when cold, where I find syn still feels more or less the same as new oil just blacker and contaminated.

Regarding oil temps. HPA have a post about that, and 100-110 is ideal and temps up to 140 and above are safe for syn but not ideal for pressure reasons.

https://www.hpacademy.com/forum/general ... -oil-temp/

vlad01 wrote: ↑Thu Feb 01, 2024 6:28 pm I only use one brace on my eco to Buick sump, was in the way of the headers so I have the driver side bosses milled off the sump. They hold up fine. Some VRs didn't even have provisions for those braces for the T5 and ran without just as FYI.