Citroen XM Forum

Is yours an early handbook Matthew?

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The two I checked are c1989 and c1992 I think Dean, but the info is just the same. The only distinction is between diesel and petrol engines. Regards, Matthew T.

The plot thickens. This is a page from the owner's manual XM-GB-5005.

Just checked my 1992 Citroen XM handbook. Citroen recommends for both v6 engines, 12v and 24v 15W50.
10W40 for the other petrol engines.

Diesel is 15W40. I must upgrade. Your not the only one who has slipped up there Matthew!

Just checked my 1992 manual, v6's both of them recommends 15W50.

Sorry, but this statement confuses me. Who or what recommend what?

Citroen recommend the thicker oil.

I wouldn't change from 10W to 15W, as 10W will give better cold flow. The 40 or 50 designation is in respect to the hot oil film, thus a thicker oil gives better protection in a larger clearance engine.

I have gone for Total Quartz 10W-50 to give a wide range, without the likelihood of oil breakdown, as can happen in some very wide ranged oils. i.e. if you went for 0W-50, the chances oil polymer breakdown are greater than 10W-50.

I wouldn't expect a thicker oil to be good for quieting sticky hydraulic tappets, just the opposite would be more appropriate.

Anyway, the cans say "Racing" on, so it must be the right stuff...

Dieselman wrote:
I wouldn't expect a thicker oil to be good for quoting sticky hydraulic tappets, just the opposite would be more appropriate.

Anyway, the cans say "Racing" on, so it must be the right stuff...

Depends if your issue is oil seeping out of the tappet during the night or oil struggling to get into the tappet in use but yeah I would go with that.

"Racing" is another 40BHP surely, you will probably get that just having the container in the boot!

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Citroen recommend the thicker oil.

Ahem, not before 1992 they did'nt, as there seems to have been an adjustment to the V6 advice around this time, either from a change of 'thinking', or changes to the engines. I have now found a later handbook confirming the advice given by Will and Russ, although all my other books make no distinction. It may a coincidence but it was around 1992 that the modified 24v appeared and we know that there were other changes to the 12v engine as time passed. If the adjustment was due to engine changes then presumably earlier engines should still receive 10/15W40. My two 24v although early cars have replacement later engines, therefore may need 15W50? In the end I cannot see that the distinction is that critical and especially if down to 'thinking' as 10/15W40 was deemed acceptable for the first three years of production! Regards, Matthew T.

Now the plots really does thicken as I have found different advice in four separate handbooks in my collection! It appears that a distinction for 15W50 was initially made for the 24v only, and then for both V6 engines, which was then changed again curiously with the 24v back to 10W40! The last change rather undermines the theory presented above!! I have presented the advice below in chronological order with the handbook number, although sadly I do not have dates the range is 1989/90 - 1994! Regards, Matthew T.

MTXM wrote:

Citroen recommend the thicker oil.

10/15W40 was deemed acceptable for the first three years of production! Regards, Matthew T.

How many PRV engines ate themselves alive in the first 3 years before Citroen decided to look again at their recommended oil spec then? is the question.
The 12v engine as fitted to Ovlov's destroyed Cam's at a horrific rate, same engine, same longitudinal layout as Pugs of the time and the Pug engines were fine, the only difference was Volvo recommended a different oil and a different service interval.

someone will know the dates for each handbook issue number, John may have already posted it, I will search.

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