What causes oil leaks?

[unlimited]

Yesterday I got my oil changed at a Kwik Lube across the street and the guy working on the car came in the waiting room of the place and asked if he could show me something. So we go to the car and he uncaps where you place the oil and you can see build up and a lot of residue. He said that in order to rid the engine of all of the build up I'd need to get the engine flushed which would have been 20 dollars. Seeing that my dad was paying for the oil change I called him (woke him up) and explained what the guy said and he basically told me "next time."

Anyway, what I want to know is what causes an oil leak? Because today we talked about flushing the engine and he said he's worried that once they do that, that it might dissolve something that could be currently preventing the J30 from leaking oil. Didn't agree or disagree with him because I'm not really sure what makes a car leak oil in the first place. But yep, could someone help me understand?

Bleh, and I'm mad that I didn't get it done too. Gotta deal with another 3 months of sluggish performance :S. Truthfully, if I had more money on me I would've went ahead and did it.

OH, and another quick question. Before I left my dad said to make sure I get 10W40 oil? So when I got there the lady asked what type of oil I'd want in it and I said I think 10W40 and she's like, "Is your oil leaking?" and I said, "No?" Then she suggested to just have 10W30 put in it. Soo, what's up with that?

Thanks in advance X]

[CHOPPER BOB]

OIL LEAKS GENERALLY HAPPEN DO TO POOR SEALS. SEALS AND GASKETS HAVE A DIFFICULT JOB AS THEY ARE MATED WITH SURFACES THAT CONSTANTLY EXPAND AND CONTRACT AT A DIFFERENT RATE THEN THE SEAL AND SOMTIMES BOTH SIDES OF MATING SURFACE ARE OF DIFFERING MATERIALS. ALSO A FLUSH IS NOT GOING TO STOP SEALS/ GASKETS FROM LEAKING IN FACT DISLODGING CRUDE THAT IS BLOCKING LEAKS IS MORE COMMON. HIGH MILEAGE VEHICLES THAT HAVE NEVEER BEEN FLUSHED SHOULD NEVER BE FLUSHED AS LARGER DEBRIS MAY DISLODGED CAUSING MORE HARM THAN GOOD, IF THIS THE CASE ONLY PERFORM FLUID EXCHANGES.

[CHOPPER BOB]

OH FORGOT ABOUT YOUR OIL WEIGHT QUESTION 10W40 THIS THICKER OIL AND SOME BELEIVE LESS PRONE TO LEAKING. HOWEVER YOUR CRANKSHAFT NEEDS TO SPIN THROUGH THIS OIL ALSO AND WILL NOW HAVE A LITTLE MORE DRAG WHEN DOING SO, LIGHTER WEIGHT EQUALS MORE POWER.

[coolyun_98]

Two kinds of oil seal

1) Statinary oil seals such as oil pan seals should not leak with flush.2) Rotational oil seal (90% of the oild seals) will VERY LIKELY leak after flush.

I flushed my J30 with BG Engine Purge (solvent based) an year ago abd the camshaft seals started to leak.

If I were you, I will try non-solvent based flush agents such as auto-rx.

[unlimited]

Thanks for the responses! Confused about something though.

Chopper Bob, were you saying that if I get an engine flush that it'd cause the leak? Right now nothing in my car leaks but my dad thinks that nothings probably leaking (the oil) because everything's blocked off by all of the gunk and that flushing will take it away and start causing problems (he's assuming the engine has never been flushed, he's never looked at it). And so the 10W40 means it'd drag more since its thicker? They went ahead and put 10W30 in there so thankfully I didn't insist on the other one, lol. The car right now is dragging enough as it is

Coolyun, so would it certainly not leak if a non-solvent product was used? I'm not sure what they were going to use at Kwik Lube but thanks for the heads up! I'ma ask next time and make sure nothings gonna get damaged.

[driverdriver]

The oil pan on the J starts to leak over time, its age related. Mine needs tightening every once awhile.

The front seal is know to deteroriate over time. A new seal is cheap and any competent mechanic should be able to replace it.

http://www.nicoclub.com/FSM/J30/1994_J30/em.pdf

[yodawill2000]

Driver.Any chance the oil pan leak could get to the exhaust ??Need to get under there and see.

I have a very slow leak only when driving that occasionally hits the exhaust and throws off a bit of smoke.I assumed it was a leaky valve cover that I plan on addressing soon.I would MUCH rather tighten the pan bolts than pull the plenum !!

[coolyun_98]

A lot of people report wonderful result with auto-rx. I am not sure what exactly the chemistry is but auto-rx works more gradually than solvent based flush agents.

Peopl claim that not only it flush your engine, but it also stop oil leaks in most of the cases.

[unlimited]

Thanks Coolyun!! Yeah I read around after you mentioned it, seems like a really good/safe product. I'ma definately try it with my next oil change, which means I'd probably be doing the flush myself. Glad I came here and asked, and really glad I didn't go through with it yet.

[yodawill2000]

Anybody know what chain store carries Auto-RX ??Or do you have to buy it off their website ?

[GerryO]

For me there is no substitute for taking something apart to clean it (at the same time replacing old gaskets, o-rings and seals) as opposed to some sort of chemical flushing treatment that may expose other parts to non-lubricating solvents and loose debris.

Someday I'd like to drop the oil pan on my engine, but until then making sure the old oil is hot when it is drained is the next best thing. And sluggish performance is not very oil weight/viscosity dependent at all.

[unlimited]

so then whats the difference between 10w40 and 10w30? just thickness?

[yodawill2000]

Its how viscous the oil is at a low/high temp

let me see if I can find the post Q45Tech made about it

[driverdriver]

"Driver.Any chance the oil pan leak could get to the exhaust ??Need to get under there and see.I have a very slow leak only when driving that occasionally hits the exhaust and throws off a bit of smoke.I assumed it was a leaky valve cover that I plan on addressing soon.I would MUCH rather tighten the pan bolts than pull the plenum !!"

It's possible depending on where the leak is. Mine is in the front of the oil pan. Tightening the front bolts alleviates it.