Just replaced my oil pan gasket. It must have boosted up the oil pressure because now I have a nice steady stream of oil which starts at the top of the front rotor housing and makes its way down to the ground. It is located on the front housing on the top, where "MAZDA" is inscribed. The little stream runs right down the engine in front of the spark plugs (forward of them). Is this a common spot for leakage? Does this call for major overhaul or what? How much? Any suggestions? I just switched from 5W-30 motor oil to using 20W-50. Did this because it is getting warm out there. I wouldn't think this would be a cause because 20W-50 is thicker...right??

Mark

 

Oh yeah, good ol' dowell pin leak. Calls for a rebuild, maybe not a complete...but I figure if you got the damn thing open, just do it all anyway.

 

First thing to do is to drain your oil and switch back to 10w30 or 5w30 if that's what you were using before.

Your oil pressure is driven by oil viscosity, which is much higher when the oil is cold, the 30/50 trailing suffix. When the oil gets warmed up, it acts like thinner oil, the 5/10/20 prefix. So, when you use a thicker oil like 20w50, it willl increase oil pressure above normal until you get it up to temperature, then it will still maintain higher pressure due to higher viscosity.

If your engine only leaks when you use higher viscosity oil, then go back to the thinner cold/hot oil mixture to get the leak to stop. In most climates, 10w30 is the best rating. You only need to go to lighter oils when the temperature is consistently below freezing on cold start, and to heavier oils when the temperature is consistently above 100deg F on cold start.

This is to ensure adequate lubrication for the engine and maintain oil pressure.

 

I think you've got it backwards long duck. From what I understand, the prefix is the cold viscosity, w=winter, then the suffix is the hot viscosity. But your reasoning is correct.

 

What about those stop leak additives?? Recommended or no??

 

Besides, doesn't the fact that I switched from 5W-30 to 20W-50 mean that the oil that is now in there is thicker?? Higher the number, thicker the oil. I would think thicker oil would be less susceptible to leaking through cracks than thinner oil. Right??

What about those stop leak additives? Recommended or no?

 

Multi viscosity oils work like this: Polymers are added to a light base (5W, 10W, 20W), which prevent the oil from thinning as much as it warms up. At cold temperatures the polymers are coiled up and allow the oil to flow as their low numbers indicate. As the oil warms up the polymers begin to unwind into long chains that prevent the oil from thinning as much as it normally would. The result is that at 100 degrees C the oil has thinned only as much as the higher viscosity number indicates. Another way of looking at multi-vis oils is to think of a 20W-50 as a 20 weight oil that will not thin more than a 50 weight would when hot.

 

i used some of the stop leak and it works great, the only thing you have to watch for i believe is if there is a crack anywhere then the stop leak wont work, it does little leaks. also dump some lucas lubricating oil, the stuff is great.

 

I would say not to use stop leak as oil is injected into your engine, I would think that it would just be a good idea to keep it out of a rotary engine, but what do I know. I'm sure it's going to be such a small amount it wouldn't do much harm or any harm at all.

Any Rotary Professors want to lend us "nubs" a hand?

 

I'd recommend a rebuild, but it's a big, expensive step for some people.

 

The bare minimum is a gasket set swap, which costs around $100 from Mazdatrix. Or at least the older four port 13B gasket sets are around a hundred. You might as well replace other things that are in need at the same time, as well as cleaning (porting) the casting flash from the ports etc. I mean, you might as well with the engine apart, right?