Full Synthetic?

[theminordetails]

Is full synthetic motor oil required for a 1997 740i?

[jayy781]

yes, as far as i know. ive been using mobil 1.

[theminordetails]

What weight are you using?

[brettski]

Given a choice of
Mobil 1 EP @ $12.68 per litre
Shell Rotellla Syn @ $10.37 per litre
Redline @ $24.31 per litre
What would you use in a E38 740iL??
http://cgi.ebay.com.au/Formula-Shell...item27aee74005

[jimmythepie]

Originally Posted by brettski

Given a choice of
Mobil 1 EP @ $12.68 per litre
Shell Rotellla Syn @ $10.37 per litre
Redline @ $24.31 per litre
What would you use in a E38 740iL??
Formula Shell Full Synthetic Engine Oil 5W30 5.676L Box - eBay Other Engines, Components, Engines, Components, Car Parts, Accessories, Cars, Bikes, Boats. (end time 06-Feb-10 23:30:36 AEDST)

i can see where your at brett but im sure others will disagree

[marti5]

Mobil 1 for me....

[BigT's93]

Interesting. The PO did not use Full Synth Oil. So the first oil change I did I used Mobile 1.
my 93 740il started leaking a bit. So I tried Castrol GTX Synth Blend, no leaks. I've heard FullSynth on a high mileage engine will cause leaks. I guess it's true.

[beamers4life]

Big T's right changeover from regular to full synthetic on a high mileage will cause leaks and inadequate lubrication. My advice if it hasnt had synthetic yet then dont use it.

[brettski]

So the normal engine oil is a 10W40, is a 5W50 going to be ok?
Will it give a better range of temperature protection?

[theminordetails]

The only oil/weight that I found that matched the API rating in my owner's manual was Mobil 10W-30 non-synthetic motor oil. I have 135K miles on my car and don't believe it has ever used sythetic.

[marti5]

Now you've lost me...why ask the question in the 1st place when you know what your car requires ?????, if it has full BM history its always been given the required oil....10w/30 or 10w/40 will be fine, full syn/semi syn or mineral will all be fine....they all mix with one another...

[North]

I've heard conflicting views on switching from organic to partial synth/ full synthetic on high mileage engines.

Some say that it is bad because synthetic oil will slowly remove the organic buildup deposited by organic oil which supposedly helps keep the engine sealed. They say this causes leaks (like you experienced).

Others say it is good because of superior lubrication and operating temperatures, which they say adds HP due to a reduction of friction.

Its hard to tell which is the better option, and reading more conflicting views makes my head spin.

[brettski]

I am just trying to figure out whether 10W40 was the standard for the time the car was made, or if 5W50 or 0W40 was readily available, that would have been recommended.

Not knowing a lot about oils, does the 5W50 option offer the equivalent protection of 10W40 plus more, or are there trade offs with the wider range?

[1LOBOSS]

This will sound snotty but I always buy new and Mobil 1 syn always goes in at the 10 mile point. Waste of money maybe but 80-100.00 is cheap peace of mind.