Why are Lubricators advised by some for LPG

[Martec]

I was advised by an 'expert' to fit a lubricator to the inlet manifold for when using LPG (the manifold vacuum draws in a 'special' oil to lubricate the valves and seats).

Question 1 is it only advised with some or all engines, old or new?

Question 2 What is the oils constituants?

Question 3 Where can it be bought from?

This is for a 1961 Jaguar XK engine with unleaded valves and seats.

Thanks

Brian

[rossko]

Question 1 is it only advised with some or all engines, old or new?

Only some, search this forum for the brand name 'flashlube' to get some ideas.

Question 2 What is the oils constituants?

Trade secrets and pixie dust. I believe the bulk of the oil is just a carrier for the magic parts.

Question 3 Where can it be bought from?

http://lpg-kits.org.uk/shop/valve-protection/cat_3.html
amongst many others, but that handily lists two of the leading brands
http://www.jlmlubricants.com/valve-save ... works.html
http://www.flashlube.com/en/company/the ... story.html

This is for a 1961 Jaguar XK engine with unleaded valves and seats.

A great unknown; to what spec are the 'unleaded' seats? Don't tell me, it wouldn't help decide, there doesn't seem to be lots of knowledge like "this metal is fine and that isn't", plus it will almost certainly vary by subtleties of engine design and fuelling setup etc.

If it were mine I'd gamble without lube, the chances are the 'unleaded' seats were over engineered for that task and will be fine with the slightly harder LPG task.
In case of nervousness it would be possible I think on the XK to measure gaps, run ten thousand, and measure again.

Modern cars that suffer problems on LPG seem to be those where high tech quality control and engine management allows them to be just good enough to work with unleaded and its expected additives.

Have you seen
http://www.go-lpg.co.uk/XJ6.html
no suggestion there of flashlube for (admittedly later) XKs, but then I think the seats were upgraded for the XJ car. Might be worth a chat with them especially if your 'unleaded' seats are simply the later standard part.

[Martec]

Thanks for your reply with so much information.

I rebuilt my XK engine in 2000 at the point when unleaded fuel was coming in and no one seemed to know what effect it would have on old engines. A very good Scottish machinist replaced the seats and valves for me and in the 30,000 miles it has since covered (yes I know not much), two of the tappet gaps (cam to bucket) have only closed by 2thou and that was within the first 3000 miles as it bedded in, no closing since.

Subsequently it would seem the original seats and valves (in an alloy head) were fine for unleaded, not sure about for LPG.

I've spent the afternoon removing the inlet manifold (very tightly packaged) to tap for a vacuum point but also for the lubricator connections. With your advice I'll fit two blanking plugs so it can be fitted at a later date with the lubricator connections if necessary.

Thanks again
Brian

[billynoband]

Strange how jlm and flashlube both claim that using any other make of magic fluid will block the filter and void the warranty.
My flashlube system seems to work well anyhow. No more hunting tickover and I have covered more miles now with it than before which caused the rescession.

[Ricey155]

I was advised to have flashlube installed on my 2004 Type R

ive reverted to JLM luve from eBaY its loads cheaper than Flashlube, hopefully its doing some good

i was told the additive in petrol keeps the valves in tip top condition and LPG doesn't have this so you get FLASHLUBE instead ???

[Gremlin]

An engine reconditioner once told me that the Stellite valve seats they fitted to old heads on the grounds that everything would burn up with un-leaded, but never did..... were the same as he fitted for LPG engines........ Not dual fuel, just gas.... because the then 4 star petrol lubricated the valve seats if you ran on petrol for 10% of the time...........

[rossko]

Last week I had a quick peek at a Flashlube system (the simple draw-through bottle) which had stopped using fluid. It was filled with JLM fluid - though I wouldn't like to say that something else altogether hadn't been in there in between the original Flashlube content and the JLM.
Anyways, no flow due to the filter sock not passing the fluid at all. Up to the user, I guess he could discard the sock and it would work for a while until some grit got into the needle valve.

Upshot is ... I would recommend keeping an eye on fluid consumption if using non-standard fluids in any system.