General After Run Oil, Overrated?

bigone5500

Well-Known Member
I have been watching some videos and reading up on nitro rc stuff. One of the things that has cought my attention the most is the mention of WD-40 used as after run oil. The mention of this is in the traxxas manual for the Tmaxx. This has got me wondering if after run oil is really overrated. Is there something in the oil that is really necessary for nitro engines? After all, we're simply displacing the effects of the nitro fuel to absorb moisture right? WD-40 does this well but does it do it well enough for RC? In my mind, if the manufacturer puts it in their manual then it must be good enough right?

Opinions?

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Tony

Staff member
I have always used after run oil. Methanol (and all alcohols) are hygroscopic meaning they can pull moisture from the air. This moisture will cause a white powder on aluminum (it's actually aluminum oxide, same thing that is created when anodizing) and obviously rusts steel (iron oxide) which the bearings are made out of. As you stated, WD-40 will do the same thing and you can use if if you want, it just doesn't have the lubricating properties of after run oil, although it does have some.
 

bigone5500

Well-Known Member
I was talking with the owner of the local hobby town and the subject of after run oil came up. During that conversation, the likeliness of it to marvel mystery oil came up. Has anyone actually used MMO in their engines?
 

Geena

Staff member
I have never even owned a bottle of after run oil. My engines never sit for more than a few days between runs, and I run YS engines. YS says not to use after run in their engines because they use silicone O-rings, and after run will damage them.
 

bigone5500

Well-Known Member
I have never even owned a bottle of after run oil. My engines never sit for more than a few days between runs, and I run YS engines. YS says not to use after run in their engines because they use silicone O-rings, and after run will damage them.
Have you ever used wd40 in your engines?
 

bigone5500

Well-Known Member
I need to get my nitro plane out and clean the engine. It hasn't ran for years. It may not be any good. It's a Thunder Tiger Pro .46 Ball Bearing.
 

bigone5500

Well-Known Member
I bought a quart of marvel mystery oil today. I wanted to see what the differences in oils are between it and after run oil (I have Radient branded oil). A couple drops on a piece of white card shows the exact same color. The consistency of each one is almost the same with the MMO being a little bit thinner. The odor of each is totally different. MMO has a detergent smell whereas the ARO has more of a glow fuel odor. It's that which has me thinking that the after run oil is the better one to use. However, MMO states on their bottle that it will "Neutralize corrosion from water contamination". It also states that in gasoline engines it lubricates the top of the cylinder and also enhances lubrication in the crankcase. But these are two totally different engines using totally different fuels.

I think I'll get a small bottle and keep some of this in it for the bench and pour the rest in the gas tank in my truck.
 

Tony

Staff member
I DEFINITELY would not put any more oil in the fuel. They are specifically measured with the correct amount of castor or synthetic oils to lubricate the engine. If you put more oil in the fuel you will never get it to run correctly.
 

bigone5500

Well-Known Member
I've used sea foam in my fuels but not MMO. We'll see how it works out. I gotta get off my rear and change the plugs out.
 

Tony

Staff member
Seafoam is great especially if you run it in your fuel, oil AND suck it into your intake via the brake booster line and let it sit for a while. smokes more than willy nelson, but it will clean the crap out of your engine!!
 
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