Thanks Dewfpo on the idea for mixing the two-I have heard that 40wt Mobil was more like 30wt in other oils(syn oil only) so 50 may be like 40. Sevenvolvos-as far as your mileage going up like it did-I read the thread and agree with Paulii, not to worry about it. My car has seen it's high mileage as my main sales car with lots of miles to go before (I sleep)the next call. I have seen the mileage go up and down for no reason like that for years. You may have gotten some really good gass that helped clean a lot of carbon off the top of the cylinder head or cleaned the 02 sensor where it was working better-but it boils down to don't look the gift horse in the mouth. As far as the blow by-the pvc is working fine about taking care of the gasses and all-I'm just trying to find away to stop the blow by from happening, or decrease it. I'm not into doing another Auto r-x treatment and not sure on how to handle it but had always heard by going up to a heaveier wt in oil that it would decrease the useage.
Thanks
Poolman