Citroen XM Forum

Handbook says 10w40, but fully synth or semi synth? ECP have an offer on and the missus has been paid, so want to get an oil change done!

2.0 turbo petrol. Need to sort my signature out!
Cheers

Sam

fully synth is what was put in last time - as Halfords had a special offer on and I got a set of free screwdrivers for ordering on line.

Sam, if you live near a Costco pop in there and pick up a 20l drum of their Chevron 10W/40 stuff. It's very cost-effective and I use it in all mine. In fact I'm currently running all mine on Costco diesel oil..

The stuff Costco flog is made by Chevron and more than adequate for the job as it meets all current specs. and the nice thing is you can afford to change it at regular intervals. I change at between 3 and 4K.

ECP and GSF can do some very good deals on filters.

...or if you live in the westcountry, Trago Millls do Comma semi synthetic for around £13.00 for 5 litres.

Peter

Comma is perfectly good oil. I believe Halfrauds own-brand is in fact Comma...

Our local factors flog mostly Comma lubricants and I've used their stuff for years, including engine oils when I can't get to Costco, and never had a moment's bother with any of it..

They are one of the few who make a good 75W/80 gear oil suitable for Citroen gearboxes...

I got some 5w40 fully synth in the end. Jim, I do have a Costco card, but its a trek to get there. I'll pick some up when I go though, the Mrs's car uses the same stuff so that will make it cheaper. I always change both every 5-6k too, makes them run much better. Cars less Tickety now it has fresh oil in! Wish it would make it more economical though!

CitroJim wrote:Sam, if you live near a Costco pop in there and pick up a 20l drum of their Chevron 10W/40 stuff. It's very cost-effective and I use it in all mine. In fact I'm currently running all mine on Costco diesel oil..

If it is proper diesel oil, you shouldn't run petrol engines on it as the ash that is there as an acidity control gradually builds up on the piston crown and can lead to pinking.
Both my XM are on the Chevron diesel from Costco.

That's interesting Will. Never even remotely suspected anything like that nor heard it mentioned before.

How come then that diesel oils carry both a C and S rating that suggests they are OK for use in a spark ignition engine?

Makes sense in a way as I always understood the only significant difference in the oil for diesel engines was a greater detergent action. Presumably if the detergent has nothing to do as it will in a petrol engine it gets up to mischief...

CitroJim wrote:That's interesting Will. Never even remotely suspected anything like that nor heard it mentioned before.

How come then that diesel oils carry both a C and S rating that suggests they are OK for use in a spark ignition engine?

Makes sense in a way as I always understood the only significant difference in the oil for diesel engines was a greater detergent action. Presumably if the detergent has nothing to do as it will in a petrol engine it gets up to mischief...

A diesel specific oil will say not for use in petrol engines, whereas an oil suitable for both isn't a diesel specific oil

The added detergency will clean out a petrol engine and hold any contaminants in suspension better than a petrol oil.

Ahh right, OK Will. That's more understood. The stuff I use has both a C and S rating so presumably is OK for use then. It says nothing about it's use being expressly forbidden in a spark ignition engine...

More of a general purpose 'fleet' oil which is OK in both I suppose...