X/Flow Engine Oil

[A7 OOH]

What is the oil of choice by X/Flow owners.

I understand 15W/40 as the grade and that fully synthetic is out.

Are we looking at a standard mineral oil or is part synthetic acceptable? 

[Roger King]

No problems with synthetic. We used to run all of our X/Flows on Mobil 1 from the late 1980s. I confess that I can't remember the grade, but 5W/50 comes to mind.

There are a lot of myths about synthetics including oil leaks and failure to run-in, but most of them are either groundless or only apply in a very few specific cases. However, you'd be advised to make sure your engine is flushed first by running with some fresh ordinary oil to try and remove any sludge. You can get flushing oils, but I've never used any so can't comment on them; they may be fine if used as per instructions.

It's more a question of the engine's previous history. Unless your engine is extremely old (several decades), it is highly unlikely to have seals made of a material that would be affected by synthetics and it is presumably fully run-in by now. So it comes down to the question of "is it worth the cost?" and I would say that this depends on the condition of your engine. If it is heavily worn, I'd say no, but if in good condition yes. 

I am aware that Mobil now do versions claiming to be suited to higher mileage engines but I've never had any experience of them.

What I can say is that engines run on synthetic from new are always much cleaner inside, with less sludge and much less charring on the underside of the pistons (which is just about the hottest part of an engine).

[harrebe]

 

Classic XL SAE 20W50 from Castrol.

 

 

[Richard K]

Millers Oils - COR 20w50 Part Synthetic

Richard

[A7 OOH]

Thanks Guys

Roger is the engine guru and I take on board his knowledge, you pay your money and take the choice at least I know the views of X/Flow guys

[Golf Juliet Tango]

I respect Roger's opinions enormously but I'll put in whatever my engine builder tells me to use.

[Sooty]

Without going stupid with the plastic money  and given that most modern oils have reduced zinc content and Crossflows need zinc to improve the cam and rocker lubrication I have been persuaded that Valvoline VR1 20w50 is as good as it gets.

You may hear recommendations re additives and there are many versions of snake oil out there but ZDDP will improve to zinc content of the modernised multigrade.

Ive tried 10w40 and feel that it is just a bit too thin for my crossflow with extra carry into the catch tank when given a good thrashing.

[Golf Juliet Tango]

I add ZDDP, as agreed with the engine builder.

[eric]

I use Motul 300V 15 w 50  Fully Synthetic  . Nice oil . I will not change after some 10w40 Semi Synthetic .

The Motul is much better . I have done a lot of miles, more than 100 000 

[HendrixsWhiteStratReturns]

I run on Valvoline VR1 20w50 and have been told that is the one for older Xflows but the others mention here as just as good 

[Iamscotticus]

Caterham Recommends Mobil1 on my engine plaque.

Mobil1 fan boy here, but I too have read about the zink.  I think it would depend on the build spec.

Perhaps a "run-in" oil with high zinc for a short time after a build fo the tappets and cam to bed in?

[Golf Juliet Tango]

Caterham Cars recommendations change.  It depends upon which supplier they have a deal with at the time of manufacture/supply.