The weight of the oil, the type of base stock used and additive package all play a role. I think it is more about HTHS and additive package. Their is a reason that all of your heavy duty diesel engiens wich also have really high slideing and rubing loads on the valve train all use 40Wt. oils!
To the best of my Knoldge their is not an OEM that recomends 0W30,5W30 or 5W20 in an industrial diesel used in over the raod trucking! It will take a huge improvement in materials, treatments and oils to over come this!
I have used synthetic oil since 1975 and never once experienced any engine noise. I find it unusual for that to happen and suspect it has more to do with the brand of oil filter in use than the oil. I know of many instances of those who claim to have this noise that disappears when they use another brand of oil filter. Also when people switch to synthetic oil, they get all the old tales of engine noise, leaking seals and oil consumption. Prior to installing the oil they most likely paid little attention to leaks and noise but now there begin to hear things that are really normal start up noise and most likely was there all along.
Can you imagine all the BS I got back in the 70's and 80's when people found out I used synthetic oil.
We had a 1994 Dodge 1 ton van at work and just about every time that van sat for more than a day, the lifters rattled for a few seconds on start up. It never got synthetic oil, every oil change was something different.
Hi, This sort of relates to what I have been talking about in another area.
A lot of engine builders in Aust are not keen on full PAO synthetics. They claim that roller rockers usually suffer from a lack of lubrication in high performance applications.
A well known racing and engine building company also claim that Valve Train parts also suffer from lack of long life
out of various valvetrain components with Synthetics.
A major Head and Valve Train component company here void all warranty if your found using a Syn oil with there products.
A major Cam company here also strongly advises against the use of Syn oils with there Cams.
Even Crower Cranks make a comment in there FAQ section on there web site, that the possible ware and damage effects of Syn oils in V8 engines far out way the slight HP gains and only recommend the use of quality mineral.
I believe that with the large valve sizes (2 valve cylinder), low (relative) revs (7500) but "high" lifts via the pushrod and associated translation devises, the cam followers, rockers the stressed interfaces on these items appear to benefit from the characteristics of the mineral oils.
While Technically Speaking they don't compare to Synthetics, this being in a tube in a lab, and more so on the advertising brochure. However on the Tar in an engine I go on word of mouth combine with revenant Technical data. I make it very clear I am no expert, only a student of Oil, and I feel that yes in curtain applications they are great things. But don't write off the Old reliable Mineral Oils just because the broachers aren't as shinny. Sure you do have to change it more often, but I like the thought of always having clean oil in a clean engine.