I always lube crank/camshaft seal with clean motor oil.

As I understand it, it's not the seal that's machining the crank (because, yes, rubber is a lot softer than steel) but dirt and grit that get caught between the seal and the crank.

--Ian

^ yeah, that makes sense. Probably why it is not consistant on every vehicle. Dirtier oil and environment would most likely cause a deeper groove.

So much bad information in this thread...

1. There is obviously oil behind the crank seal. If there weren't, we wouldn't need the seal. (Air cooled VWs didn't have "front" crank seals, and despite a slinger plate and spiral grooves cut into the pulley, still leaked from this among many other locations.)

2. Nobody said that this oil was at full system pressure. (Looking at you here, 18psi.)

3. Still, the inside of the crankcase can, at times, be under some pressure relative to atmospheric. (Blowby much?)

Seriously, I didn't know we had so many noobs.

See post #19, 22, and 24 for some decent information.

You guys can't be serious.

1) rubber isn't gonna cut jack diddly into a forged steel crank. dirt/rocks getting in between the rubber and metal causing the groove is A COMPLETELY DIFFERENT STORY, and not in any way shape or form the same thing as the original statement.
2) yeah duhhhh....however these guys are hinting that "oil can push out the seals". which is not the case. it is there, but the seals keep it from splashing out, and just contain it inside, there is no oil pressure whatsoever behind there
3) yes, blowby gasses and all that. exactly what I was talking about. gasses pressure, but not oil pressure.

I feel like you both are trying to troll me with this retardation, and I feel like the n00bs are being completely misled. Mazda doesn't put oil or grease on the seals when installing them. So if you want to, It probably doesn't hurt and it probably helps get them in easier, but gimme a break about all this other nonsense

I have 2 genuine Mazda cam shaft seals in my garage and they both have grease on them straight out of the packet.

So do I, from Rosenthall Mazda, and they don't.....

I'm not gonna argue about it, since either way should work and be fine, my issue was with the whole "groove" and "oil pushing them out" statements.

Tomatoes, tomadoes Vlad. The seal won't scrap the crank without a little dirt, the dirt won't scrap the crank without the seal, what of it? No one here is trolling, serial.

One of my racer friends used to cut the lip off the wheel bearing seals on his race bike in order to reduce the parasitic drag it caused. The big drag reduction technique was to run aluminum shavings through the water pump (NOT on the bike at the time) until it loosened up. Really. At 12k rpm even a loose water pump ran more than enough water through the engine.

No, this type of stuff is not for everyone.