moly and moly coated pistons

[n8wvi]

My car (and 2 others I change the oil on) has moly coated pistons. All 3 vehicles have > 80,000 miles and all 3 have classic pistons slap. Here's the question, for a NEW car with moly coated pistons, would using an oil with moly protect this coating better than using an EQUAL oil without moly?

Dave

 

[sbc350gearhead]

My uneducated guess would be yes.........but perhaps you should PM molakule or terry about this question........seeing as how noone has chimed in.

 

[n8wvi]

Anyone

 

[Silverado]

I'm running Speed Pro hypereutectic coated pistons. However I'm not sure if its moly. The coating looks cool, but I'm not sure if its just a marketing gimmick. Does anyone know? (the coating is black)

 

[Chris B.]

What brand are these engines and it what car?

 

[n8wvi]

Mine are Subarus. Subaru started using moly coated pistons in the mid 90s.

Dave

 

[MolaKule]

The moly coating is most generally on the piston skirts, and is a solid film coating used to reduce wear and friction on the skirts. This offset writ pin design has high side thrust loads which gives rise to piston slap in some engines. Piston slap can be reduced by using Schaeffer's #132 to reduce the shock load.

 

[sbc350gearhead]

quote:

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Originally posted by MolaKule:
The moly coating is most generally on the piston skirts, and is a solid film coating used to reduce wear and friction on the skirts. This offset writ pin design has high side thrust loads which gives rise to piston slap in some engines. Piston slap can be reduced by using Schaeffer's #132 to reduce the shock load.

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Mola....if the piston slap issue is due to high thrust loads, then would increasing the R/S ratio help?

 

[n8wvi]

Mola, glad you checked in. Could you answer the original question? I'm trying to prevent the issue in the first place with 2 new Subarus. The three older ones we just live with.

Dave

 

[MolaKule]

n8,

I would say that would help.

The reason I suggest #132, is that the moly will reduce friction while the antimony will reduce wear.

The ELCA surfactant in #132 also seems to have a cushioning effect for the "shock" loads created by piston slap.

R/S ratio, yes that would help unless there are other constraints in the system that did not allow you to modify the engine design.

 

[giant_robo]

Maybe something thicker than a 10w-XX would stand the shearing better and provide more cushioning; try 15w40 for summer and mild winters.

Aside from this regarding #132:
If I wanted to get 4 or 5 bottles of #132, do I go through the Schaeffer online store and call that number, or do I go through one of their distributors? Does Bob sell these, or who does? I'm in on the West coast, if that matters, shipping-wise.

 

[John in the ATL]

Tim Mills is a site sponsor. I believe he is the guy for smaller orders.

http://www.bobistheoilguy.com/salesreps/AR_reps.htm

 

[Santo Fontana]

This conversation is interesting because I have a subaru which I believe has moly coated pistons, and I have been using a moly-less oil.

Ironically I hear less cold startup slap/knock/tick with the amsoil than with RP and M1.

Is it worth switching oils? Maybe I will give Torco a try.

Also I dont know if Subaru engine builders are addressing the rs ratio. Magnus, Axis, and I-Speed are some builders if anyone wants to check them out.