LC100 Castrol/Mobil Synth S

Submitted: Thursday, Apr 24, 2008 at 10:47
ThreadID: 56951 Views:3555 Replies:5 FollowUps:1
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I have a petrol lc100 (6 cyl) which I serviced at Toyota up until 140,000km. They used Castrol FMX/Magnatec (I understand Magnatec is the retail equivalent of FMX). I never had to top up the oil up until this point. At 140,000 I change to a local mechanic who used Mobil Synth S. Between 140,000 and 150,000 I had to add 3 litres. No sign of leaks so it’s going out the exhaust pipe. The mechanic is at a loss as to why, as is Mobil tech support. Wondering if anyone else has had something like this ? Synth S is supposed to be good but I'm thinking of trying castrol again.
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Reply By: Stephen M (NSW) - Thursday, Apr 24, 2008 at 11:54

Thursday, Apr 24, 2008 at 11:54
When we bought our commodore brand new after the first oil change I changed to Mobil1 synthetic. Virtually straight away the engine was as noisy like you wouldnt believe and the tappet noise was dreadful. I dumped it staright away (2000k) and went back to castrol used by the dealer. I was then informed not to use fully synthetic oil with roller rockers will stuff them totally, now in saying that Holden recomend fully synthetic in all there HSV vehicles and guess what have the same heads minus a few valves as the ecotec V6. And the 2000k the oil was in there the level dropped by about 3 mil on the dipstick what that equates to in mls I dont know as I dumped it. Not sure what sort of tappett gear is in the cruiser but maybe similiar. Regards Steve M
AnswerID: 300240

Reply By: Bushtrek - Thursday, Apr 24, 2008 at 12:31

Thursday, Apr 24, 2008 at 12:31
You have a classic problem of changing to what you/or the mechanic thought was a better product "because it is synthetic or part synthetic".
A great myth, that no amount of explanation to the contrary will convince, some people to disbelieve.

A very real possibility exists that the mobil product contained too much volatile base fluid and what you see as oil consumption is in fact the base fluid evaporating out of the system during use. Yes, it is going out the exhaust via the rings into the combustion chamber, also out the PCV system into the same destination.
The oil is a vapour by the time it transfers into the combustion chamber.

You would be better of using the Castrol Magnatec 10W-40
AnswerID: 300244

Follow Up By: Member - Olcoolone (S.A) - Thursday, Apr 24, 2008 at 15:10

Thursday, Apr 24, 2008 at 15:10
Have to agree with Bushtrek, alot of people think synthetic or semi synthetic is the bee's knee's...sure it is good but in the right application.

Nearly all hi tech deisels use a semi synthetic now due to the extra load placed on oils and longer service intervals.

Most non synthetic oils are very good and work extremaly well.

I doubt very much if the average person could tell if the oil they are using is working good or bad.

Just because you go through oil quicker than some other brand does not mean it is cr%p.

Much the same as people using oil additives.....WHY?

The only thing you are helping is the person or company who sells it.

Im sure alot of people who say brand X oil is no good and you should be using brand Y only do so because they don't want to be like everyone else and use brand X.

Regards Richard
FollowupID: 566408

Reply By: MrBitchi (QLD) - Thursday, Apr 24, 2008 at 13:07

Thursday, Apr 24, 2008 at 13:07
Some oils seem to work better in some engines than others. You've found that Mobil Synth S is no good for your application whereas others swear Magnatec is rubbish, yet it seems to work fine for you...

Go figure ;-)
AnswerID: 300252

Reply By: Member - David P (VIC) - Thursday, Apr 24, 2008 at 13:26

Thursday, Apr 24, 2008 at 13:26
The old Commode was an anvil compared the modern micrometers on the road today which have much finer tolerances....silverback
AnswerID: 300254

Reply By: Ianw - Thursday, Apr 24, 2008 at 20:43

Thursday, Apr 24, 2008 at 20:43
I have been using Mobil Synth S/ Super S for 30 000 ks in my Navara ZD30 . Hasn't used a drop of oil between changes every 7500ks. Car has done 130,000. Changed to Synth S/ Super S due to Nissans revised oil specs for the ZD30.
AnswerID: 300309

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