Engine Oil

[robert_e_smart]

Chaps,

It has been a while since we have had a debate. So let me kick things off.

Do any of you use semi-synthetic or fully synthetic oils in your XMs?

I have been using the standard 15w40 mineral oil, and changing it every 4k miles along with the filter.

Is it any better to use sythetic oils and leave it in for up to 10k?

I am of the opinion that it is better to use mineral oil that is changed on a regular basis than sythetic oils that are in there for a long time.

[Ciaran]

Regardless of which oil I use, I always change it, and the filter, at least every 5k. I wouldn't feel comfortable leaving any oil for 10k, fully synth or not.

Ciarán

[Dean]

I use Castrol semi and change it every few thousand miles or when it goes golden on the dipstick.
Dont think it matters what oil you use either though, so long as its kept clean.

D

[robert_e_smart]

Well I put in 10w 40 semi last night, as my old boy used that in his C5 and read in his new C5 haynes manual that it is better to use 5w 40 in them as it eliminates problems with the Particule Filter in the exhaust. So he had enough 10w 40 left for one oil change, so I stuck that in her. I'll leave it in her for 5k, and revert back to 15w 40 mineral oil when I next change the oil again.

[Peter.N.]

I use Trago Mill best it meets the spec and used to cost about £6.00 per can, gone up to over £9.00 now although coming down. Like Ciaran, I change mine every 5k and my engines have always lasted well, the last one I sold having covered 292 k miles and still good. The green estate has done nearly 200k, 80k by me and uses very little oil. I firmly believe that the frequency of oil changes is more important than the oil you use.

Peter

[DerekW]

I use synthetic oil (5W/30) in the V6 and semi-synth in the TCT and the 1.9 ZX. I also leave it in for the recommended oil change periodicity.

I'm not suggesting that this is the best course to follow but I believe in feeding my engines the best available and by running extended oil changes the cost probably equals out.

55 years ago I was preaching to anyone who would listen that it was a waste of time and money to change rear axle differential oil (no contamination), it took another 10 years before the manufacturers came to the same conclusion. It seems to me that with modern engines with minimum blow-by we are in a similar situation.

Derek

[Peter.N.]

It still gets pretty black though!

[steelcityuk]

I would say it depends on the engine as to what oil to use, sounds obvious I know.

Generally I stick with what manufacturers recommend in terms of type and grade. Although it doesn't apply to strictly with our engines the newer engines seem to be sensitive in this respect.

Usually I change the oil twice a year for the recommended stuff. It's cheap enough from GSF.

There's no way I would leave oil in an engine for 20K no matter what the manufacturers say, they don't care if the engine's worn out at 100K by then it's out of warranty and they can sell you another car on the promise of extended service intervals...

Steve.