Parasynthetic compatibility - Schaeffer's 15w-40

[ZeeOSix]

To me it comes down to metal-metal contact protection (Schaeffer's) vs preventing metal-metal contact (JD Plus 50 II). Otherwise the two are are robust oils that fit the application.

Based on the discussion in the other thread, I had to make a comment on this. What prevents metal-on-metal contact is the film thickness (MOFT), which is a function of viscosity between moving parts. That's why it's good to have some viscosity and MOFT headroom, so there is more wear protection by keeping moving parts separated better, as discussed in most thin vs thick threads. Obviously 15W-40 already fits that bill. The 540Rat's one-armed bandit doesn't test that. If anything, it only tries to test the film strength of the oil, which is basically the AF/AW additives factor of the oil. There's a difference between film thickness and film strength. Film strength only kicks in when the film thickness goes to zero and metal-to-metal contact begins.

Machine Lubrication has a good article on it.
https://www.machinerylubrication.com/Read/30835/lubricant-film-strength

 

[siriusc1024]

Based on the discussion in the other thread, I had to make a comment on this. What prevents metal-on-metal contact is the film thickness (MOFT), which is a function of viscosity between moving parts. That's why it's good to have some viscosity and MOFT headroom, so there is more wear protection by keeping moving parts separated better, as discussed in most thin vs thick threads. Obviously 15W-40 already fits that bill. The 540Rat's one-armed bandit doesn't test that. If anything, it only tries to test the film strength of the oil, which is basically the AF/AW additives factor of the oil. There's a difference between film thickness and film strength. Film strength only kicks in when the film thickness goes to zero and metal-to-metal contact begins.

Machine Lubrication has a good article on it.
https://www.machinerylubrication.com/Read/30835/lubricant-film-strength

We have the same view on wear protection in this instance.

I was under the perhaps false impression that he didn't use the one-arm bandit. I thought he was actually measuring MOFT breakdown?

The reason why is I don't see anything about wear scar size, but there is a ksi value.

 

[ZeeOSix]

We have the same view on wear protection in this instance.

I was under the perhaps false impression that he didn't use the one-arm bandit. I thought he was actually measuring MOFT breakdown?

The reason why is I don't see anything about wear scar size, but there is a ksi value.

He says it's based on a wear scar, so it's a one-armed bandit like Project Farm also uses in his oil tests. Snip it from the 540Rat blog page. Rat540 has no way to measure MOFT.

 

[siriusc1024]

He says it's based on a wear scar, so it's a one-armed bandit like Project Farm also uses in his oil tests. Snip it from the 540Rat blog page. Rat540 has no way to measure MOFT.

View attachment 280532

I see why that blog is not taken seriously.