OK so here's the story......... Drove 2100 miles round trip during the x-mas holiday. Prior to the trip my truck was running FINE, not losing ANY oil, EVER(ok maybe 1/4 of a quart at each oil change)! It didnt lose any the entire trip, either. I changed the oil from 10W40 conventional to 10-40 Castrol Syntec right before the trip. Now, considering the trip went well, I didn't check the oil level for the last 10 days (it was full after returning from said trip).... I checked it yesterday and the oil is very dark and there is only about 0.100" visible on the dipstick! where the hell is it all going!

And no, there are no signs of seal rupture anywhere.....

Does Syntec have a habit of slipping past piston rings? is someone playing an evil trick on me? I don't know.....

Thoughts anybody?

 

ive had friends that have had the same problem but here is a good link about 1/3 of the way down. if it was me id swich back.

http://www.carbibles.com/engineoil_bible.html

 

If your not leaking then you are burning it , either past your rings or valve guides or both. How manymiles on your engine?

Didnt see that you lost the oil after the trip

 

its got 251k on as far as i know the original motor.

 

sounds like you need new piston rings and might as well do the valves while you are in there. my sis had the same prob with her yota

 

Thats alot of miles, but doesnt mean you have to be burning oil. The synthetic may or may not be the reason your burning oil now( there may be another problem that just showed up now).You could try switching back and see if the problem goes away. Why did you switch to a synthetic on such a high milage engine? Not a cut down , just wondering.

 

yea i'm with Sam...why'd ya switch?


don't fix what aint broken.

 

Sometimes when you switch to a synthetic on a high mileage engine it actually can clear out dirt that may be blocking leaks that could very easily have happened to you and caused you to loose oil. That is why i run 10w-40 High Mileage, conventional oil in my 86' 4Runner with 255K and not synthetic. Switch back to conventional and see if that does anything.

 

not sure what my logic was in switching. Didn't do my homework.......

 

Switch back to dino. I put Royal Purple Synthetic in mine when I got it and it started leaking and burning oil like a fiend (200,+++ miles). At the last oil change I went back to 10-w40 dino and the leaks are gone and I only have to add about 1/4 quart between oil changes.

 

I'll change it back...... as soon as it gets above 30F outside

 

Changed back to conventional and leak disappeared. Hope it stays that way.

 

This is why i won't run synthetic on older cars, too many horror stories about synthetic leaking. Remember these engines were designed to run on conventional not synthetic.

 

i'll run it in my '92 but i also rebuilt the motor in it lmfao


but i won't run it until i fix this dang leak!?

 

As a professional oil changer for the past 3 years, let me explain something to you all.

SWITCHING TO SYNTHETIC IS NOT THE REASON YOUR OLD CAR ALL OF A SUDDEN STARTS LEAKING.

What happens in older motors is that there is a build up of crap around the seals left behind by lesser quality (ahem. conventional) motor oils.

Those cover the seals, the seals aren't getting the seal conditioner, thus the seals go bad.

Why aren't they leaking? The gunk that is blocking the seals in the first place.

Now, throw synthetic oil in there. Highly detergent stuff... Washes away all that gunk, and now oil is able to seep through those seals. Not rocket science.

Had the better oil been used all along, the chances of having a leak at all drop significantly.

I've seen some old ass cars switch to synthetic with no problems, and I've seen some of them start leaking after the 3rd oil change or so. Just depends on the condition of the seals before the synthetic was added.

Now, as for it burning oil all of a sudden... I'd guess that since the molecules in synthetic are much much smaller than those in conventional, oil is simply getting passed the rings and out the exhaust.

Try some Restore with your next oil change, or a 20-50 synthetic. A synthetic 10-40 is actually a bit lighter than a conventional 10-40.

If that fails, go back to conventional. If it still doesn't stop... get new rings and a valve job.


Now if you don't mind, I'm going to go dump some amsoil 10-40 in my mustang. Been using it for the past 10k miles or so with none of the leaks getting better or worse.

 

I think you contradicted yourself: "synthetic isn"t the reason for leaks..followed by " throw in some synthetic, wash away the gunk and the seals leak". Well that sure looks like synthetic was the cause, and leak was the effect to me! My thought..old engine using conventional oil--don't change to synthetic! New engine, use your choice: conventional or synthetic, and stick with it. My 1 cent worth.

 

synthetic is slicker then conventional oil so any small leak gets worse with synthetic.

 

No, what caused the leak is bad maintenance. Synthetic just let's you know about it.