1995 240sx : Help I have a weird oil leak...

[Chaotic_Warlord]

Ok here's the situation.. I have a '95 240 with an ***-load of mile (pushing 240K) and I know I need to replace the valve cover gasket as it had a small leak when I bought the car (which strangely enough became almost non existant). So I was driving back from my GFs house and the check engine light came on, I'm thinking ok just need to put some oil in the ol girl and it should go out as that has fixed the CEL problems on other cars in the past. So I put some oil in it and being a complete putz I put in one quart of 10W40 (which I think was synthetic) and 2 quarts of 5W30. I started it up an ran it a few minutes and the light is still on so now I am thinking hmm must be something more serious. Now unbeknowst to me I didnt know you weren't supposed to mix oil weights so that may be part of the problem I am having which is this.

I went to go to work last Thursday and just as I pull out of the development my car starts to smoke a little at first but by the time I got 1/4 mile away it was beyond noticeable, I'm talking James Bond smoke screen here, so I turn it around and go home and borrowed my moms car to get to work. I went out on Saturday to look over the car and I have oil buildup on the exhaust tips, going from the end to about 1/2 way back to the muffler and there is oil sitting in the tips (they are wet with oil) it doesn't appear to be leaking oil anywhere else but again I had a tiny leak to begin with so my engine block is pretty filthy.

Incidently I went to change my oil today and the dip**** who changed it last used an impact gun on the oil drain plug because I couldn't get it to budge for anything even after 2 heavy dosings of WD40, so now I have to pay someone to do it for me .

So do I have a blowby problem or is there something else going on that I should be even more concerned about? The car runs fine (loss of power because its old and tired but thats expected) there isn't any crunching or grinding or backfiring, it doesnt misfire and it never smoked before I mixed the two oils. Is this a problem of synthetic mixing with 5W and making the oil way to thin or is there an internal problem that I should take the car in for and have it looked over by a professional.

I was looking to do a rebuild with new rods and pistons in the near future but I need my car up and running now, please help me figure this out. Thank you in advance.

[574-240sx]

How low was it on oil initially or was it low. Did you check the dip stick before you filled it with oil. You need to do a compression check because it doesn't look good.

[Chaotic_Warlord]

yes the oil was really low, not totally empty but almost 3 quarts low. How much does a compression test usually run and if it is in fact a stcuk piston and I do have a really bad case of blowby how much can I expect to pay for to get it fixed...even if I supply the parts. Any idea how many hours labor it would be. I just want to get it running where its not smoking as I am in fact going to upgrade rods and pistons once my GI Bill kicks in but that may not be for another 3 or 4 weeks.

[s13sr20chris]

even a compression test wont always tell you why you are burning it. 2 main reasons to burn oil. valve seals and rings. there are other smaller ones but those are the biggies.