synthetic oil and leaks

[rahiel aziz]

few months ago i start useing synth oil in my 91q actuallu had 2 oil changes with it but after 2nd oil change i noticed oil was always low i kept adding .first i didn't think much about it because even with regular oil q used to take a quarte in between oil changes.but yesterday morning i checked oil it was lower than half again i just added a qt few days ago and only driven car not even 500 miles.i took q to a shop to check it out .oil pan seal was leaking .i put a new oil pan yr an half ago.it was not leaking with reg oil.i heard so much about mobil 1 on this forum i decided to give it try .i used 10w-30 mobil 1. on 2nd oil change i put in bg moa too .car ran very smooth. after getting oil pan resealed should i stay with reg oil or use 5w-30 synth.what u guys think it was a bad idea to switch to synth oil on high milage car (2k2).i don't know what other seals are leaking.resealing oil pan is big job itself .i feel like i just shot myself in the foot by switching the oil.

[Q45tech]

Have used 10w/30 Mobil 1 for the past 200,000 miles and I see no difference in leak propensity from our standard Vavoline 10w/30.

Never had an oil pan leak in 254,000 miles but the front, rear main seals and valve covers leak the same as any other Q.

The wear benefits of Mobil 1 are from early engine use [wear reduction] suddenly changing at 200,000 miles is pretty worthless as the engine is worn badly by then. I would think changing at 100k might be useful but beyond this no.

The other attributes cold starting and overheats still hold at any mileage.

Checked the oil pressure sender. They leak every 70k [by design] same with valve covers.

[90Q45blue]

I switched to synthetic at 250k. I see no oil leaks. Dennis is right though, it won't really "buy me any time" but I do think the car runs smoother on the MOBIL 1 15w50.

Nick

[AZhitman]

I switched at 68K. Prior owner has dino oil changed religiously every 3K or 90 days.

Hopefully my engine will outlive the other components...

[rahiel aziz]

thanks for replies .i do like smooth rev engine.i switched to syn oil just wantd to see what it can do for q.few mths ago i did have little overheat due to jam pulley but after that i kept close eye on valve cover seals but never thought about pan.i hope its not notorious nyc potholes streets did the damage this will be second oil pan i lost to them.will it make a difference if use thicker oil.

[90Q45blue]

Some people that have switched to synthetic oil and had leaks have seen the problem disappear with a thicker oil. .

Nick

[Q45tech]

But 15-20w/50 weight [even synthetics] is on the ragged edge in cold temperatures.........you pick the oil that is the thinnest that will maintain hot idle oil pressure..........leaks are not nearly as important as your bearings!Even a quart a week only cost $250 per year vs an engine exchange of $5,000...........NYC gets cold sometimes.

[firstq]

Hey, while we are on the topic of oils - other day I could not resist sale on local B&M walmart clearing Mobil-1 0W-30 for $2.49 a quart - bought all that was there.

My 92Q has now 110 miles - can I use this straight (AZ weather) or mix it with a heavier grade?

Thanks

[Q45tech]

Again every engines wear [at differing mileages] is different you must go thru the process of measuring the oil pressure [accurately] at the hottest lowest idle rpm to pick the oils top number [30,40,50]. Takes about 30 minutes and a big diameter 100 psi oil gauge........so you can read to a 1 psi increment.

Because Mobil 1 tends to lower oil temperature [5-10F] and viscosity is measured at 210F [who knows what it is at 230F or 300F [in the rod bearings] or at the lower piston ring.........probably thicker than any conventional 30 weight in equal service...........maybe acts like a 30 when others are at 27.

Good idea to measure the pressure with 3,000-4,000 mile oil to see how much it rises [1,2,3 psi] above brand new oil. This will tell you when how long the VI improver additives last in your driving location and style.