Synthetic Oil on M50 Engines - makes oil leak

[The Melmaan]

Hello Guys!!!!
I was just talking to my mechanic (BMW Specialist) when I was changing my engine oil. I was asking him if I could use Synthetic Oil on my E34. He said that it is not wise because the chemicals on the Synthetic Oil is designed to do some work on the engine gaskets and protect, but if you have older engine and you are just starting to use Synthetics, it will destroy your gasket end up with lots of oil leak that you cannot imagine.
Has any of you guys experienced this???

[BillionPa]

the reason is because it cleans up all the gunk wayyyyy to fast, and synthetic flows better. if you did 3000 mile intervals on 10W30, then going to a 5W40 synthetic like redline shouldnt cause any leaks.

if you were going 10000 miles on dino, then you are in bad shape.

if the engine is gunky, pick up some AutoRX and let it clean the engine for a few thousand miles before switching to syn.

[rob101]

the reason is because it cleans up all the gunk wayyyyy to fast, and synthetic flows better. if you did 3000 mile intervals on 10W30, then going to a 5W40 synthetic like redline shouldnt cause any leaks.

if you were going 10000 miles on dino, then you are in bad shape.

if the engine is gunky, pick up some AutoRX and let it clean the engine for a few thousand miles before switching to syn.

i don't know i think most Petrol engine synthetics now have less detergents than the earlier synthetics.
i've never really had any problems with my m50 running synth (castrol edge 0w-40), sure it uses a bit of oil but meh it has 250 000 km on it. whatcha going to do? doesn't really use more than with castrol GTX 3 (15W-40 mineral) anyway. although i might switch to 5W-50 or 10W-60 synthetic next oil change.

[wingman]

I'll get a smashing for this but by using an approved mineral you shouldn't have any problems. It might shorten the engine life from 500,000 to 450,000...

[shuriken]

Hello Guys!!!!
I was just talking to my mechanic (BMW Specialist) when I was changing my engine oil. I was asking him if I could use Synthetic Oil on my E34. He said that it is not wise because the chemicals on the Synthetic Oil is designed to do some work on the engine gaskets and protect, but if you have older engine and you are just starting to use Synthetics, it will destroy your gasket end up with lots of oil leak that you cannot imagine.
Has any of you guys experienced this???

I thought it was because synthetic oil is thinner but has a better sheer rate than mineral oil, so it breaks down less quickly and keeps it's "shape" for longer. Also the tolerances and materials used in modern engines is different to older ones. I may use synthetic if I had a 540 V8 as it has plated bores and a much tighter tolerance between the piston and bore. The same applies to motorcycle oil, I use semi-synthetic and not fully for just those reasons. If in doubt then use mineral. In UK Castrol make "Magnatex' in synthetic(for modern engines) on mineral (for older ones).

[Russell]

Noticed no leakage in mine with mobil 1 and Castrol synthetics for the past 40,000 miles. However, I do have a slight oil seepage around the plugs with relatively new (35,000 miles) valve cover gaskets. of course this is a known issue with the M50 engine regardless of oil type.

[Morgenster]

I still think switching from dino to synth is good so long as you change the gaskets and oil after a max of 5000km after that. From then on Synth shouldn't give you any probs.
I don't know how well the auto-RX product works but I can't find it in Belgium anyway.
My mechanic uses synth on all the BMWs he's worked on and hasn't had any issues. I saw an M50 with 350000 km on it still using synth and without leaking a single drop.

[Paul in NZ]

when i bought my car it had 145 000 km or so and i converted to castrol synthetic straight away,no leaks,some "seeps" tho.I use it because the lower viscosity gives better protection at start up which is when almost all the wear actually ocurs.Now at 210,000 km or so.I run it for the whole service interval,if i ran dino i would swap it at half interval,so the cost is prolly about the same

[shuriken]

I thought it was because synthetic oil is thinner but has a better sheer rate than mineral oil, so it breaks down less quickly and keeps it's "shape" for longer. Also the tolerances and materials used in modern engines is different to older ones. I may use synthetic if I had a 540 V8 as it has plated bores and a much tighter tolerance between the piston and bore. The same applies to motorcycle oil, I use semi-synthetic and not fully for just those reasons. If in doubt then use mineral. In UK Castrol make "Magnatex' in synthetic(for modern engines) on mineral (for older ones).

just been looking through my car receipts from when I had my sump gasket renewed and the BMW garage used Castrol synthetic........ I'll shut up! The theory to synthetic and mineral in old engines and new, is a valid one however, but if it works then use it. Just costs abit more.

[wingman]

when i bought my car it had 145 000 km or so and i converted to castrol synthetic straight away,no leaks,some "seeps" tho.

Hey Paul,
What is the difference between a 'leak' and a 'seep'? Both to me indicate that oil is breaching the gasket. I take it that you mean that a 'leak' is like what old Jags do and a seep is like what you get from the rear main seal in an old Torana.