30 replies to this topic

[Captain Mainwaring]

Correct, the additive could affect the gearbox, and never ever use one with a PTFE (Teflon) additive, as it partly decomposes, possibly to to hydrofluoric acid, and makes the metalling peel off the bearing shells. In my case the acid completely ruined the engine, and left the inside of the gearbox bright and clean as if it was brand new. I don't know if they still sell that stuff.

 

If you look around the Miller's web site, you will find an oil which is optimised for the Mini. They are one of the most reputable but fairly small lubricant suppliers. I would not bother in a very old engine which will soon need a rebuild, but once it is in excellent order again, a very good oil will help to keep it that way for a very long time.

 

http://www.millersoi..._motorcycle.pdf

 

 

PTFE alias Teflon is a VERY nasty compound and a banned substance in many industries, particularly the tobacco industry. It degrades to phosgene gas at a relatively low temperature - phosgene will give you black curly teeth and long blonde shoes.

Edited by Captain Mainwaring, 26 June 2013 - 09:35 AM.

[jaydee]

+1 on the additives, although the cheap additives on the market are just viscosity enhancers, if they contains teflon or moly they'll easily wear out your gearbox.

[Alex_B]

I have heard using crappy oil also doesn't help, seen hellfrauds and it's comma counterpart classic oil not being good for oil pressure so an oil change with something better might help but a gauge is always useful

[BVY]

Hmmm I'll have a look in Halfords tomorrow and see what's in the additive. If it's got PTFE I'll change the oil again   another £20 down the pan.

 

So I bought a Smiths oil pressure gauge today. As well as a new ball and spring for the pressure relief valve. Hopefully I'll get time ti fit them tomorrow!

 

Thanks for the replies!

[BVY]

I got round to fitting my gauge last night.

So today on the way to Ace Cafe I was running on the point of boiling the engine. But I'm not sure if it's chicken or egg.

Is the hot engine making the oil too thin, causing low pressure? Or is it the other way?

When I left the engine was at normal temp but the pressure was really low. Like 30ft/lbs when doing 40-50mph. and dropping to about 7-9ft/lbs on idle and then the engine got hot again. 

I'm going to change the oil pressure relief valve tomorrow and see if that helps.

While I'm tinkering what else can I check or at least suspect as the cause of the problems?

[Captain Mainwaring]

I got round to fitting my gauge last night.

So today on the way to Ace Cafe I was running on the point of boiling the engine. But I'm not sure if it's chicken or egg.

Is the hot engine making the oil too thin, causing low pressure? Or is it the other way?

When I left the engine was at normal temp but the pressure was really low. Like 30ft/lbs when doing 40-50mph. and dropping to about 7-9ft/lbs on idle and then the engine got hot again. 

I'm going to change the oil pressure relief valve tomorrow and see if that helps.

While I'm tinkering what else can I check or at least suspect as the cause of the problems?

 

 

Why don't you cure the overheating issue? Years ago I had a guy come to me for help - big old Toyota Crown 6 cylinder with low oil pressure....he and a muppet mechanic had thrown money at it all over the place. 

He had two problems -  a blocked oil cooler and a failed visco fan, cure both and the oil temp dropped and the pressure went up.

[jedduh01]

Warning light is a warning light. Your oil pressure is too low.  Normal spec is 70 -80 psi at run 40-50 at idle.  Your bearings are trash. Oil pump worn. Time for a refresh.  Have crank 're ground to .010 oversize. Fit New cam and crank bearings.  Fixed... all in one week possible.

[KernowCooper]

If the OPs at the point of boiling the engine then there is some serious overheating issues, while this wont be a cure it may well running at the correct temp have a increase on the oil pressure due the the viscosity of the oil being affected by the boiling engine temp. Two issues here to look at the low oil pressure even when running at normal temp and the overheating. I get the feeling if the pressure relief valve does nothing its heading towards a strip down.

[Captain Mainwaring]

Warning light is a warning light. Your oil pressure is too low.  Normal spec is 70 -80 psi at run 40-50 at idle.  Your bearings are trash. Oil pump worn. Time for a refresh.  Have crank 're ground to .010 oversize. Fit New cam and crank bearings.  Fixed... all in one week possible.

 

If only it were so simple.

[Captain Mainwaring]

If the OPs at the point of boiling the engine then there is some serious overheating issues, while this wont be a cure it may well running at the correct temp have a increase on the oil pressure due the the viscosity of the oil being affected by the boiling engine temp. Two issues here to look at the low oil pressure even when running at normal temp and the overheating. I get the feeling if the pressure relief valve does nothing its heading towards a strip down.

 

 

Well....could be, we don't know because we don't know what temp the oil is at, but it could be. 

The OP's position now is that if he could cure the overheating issue without throwing money at it, the whilst the oil pressure is low, he now has a gauge and thus can keep an eye and see if it gets worse.

 

If money isn't an issue then fine, pull the thing out and rebuild it, but if it is, the the OP could quite possibly get a good few miles out of it just by taking care.

[jaydee]

If your engine keeps overheating, you must cure overheating first. If cooling systems is not doing his job the oil takes a lot of the heat hence the low pressure. Oils like castrol XL comma classic etc will shear down a lot with high temperatures.

[Captain Mainwaring]

It's worth noting too that once oil goes past a particular temperature (and it isn't that high) it's viscosity can be permanently lost.

[BVY]

I've got a new rad and stat. So i'm going to replace those this weekend and see how things go. Then I'll change the oil next week anyway.

I changed the oil pressure relief valve which did help. I now start off with 100ft/lb when engine is cold. Once it warms up sits nicely at about 60 driving and 20 at idle.Then once it gets hot it just drops right off.

So hopefully all will be well after the new rad etc 

[KernowCooper]

100 PSI when cold ? that way above what the normal pressure should be for a standard oil pump relief valve?

[Tamworthbay]

I have heard using crappy oil also doesn't help, seen hellfrauds and it's comma counterpart classic oil not being good for oil pressure so an oil change with something better might help but a gauge is always useful

I have used the halfords classic in my MGB GT daily, it gets a lot of abuse so is treated to new oil every three months. After a few years I have a good idea of what works and what doesn't. The halfords starts off ok but after only 500-700 miles the pressure is 10-15psi than when I use comma sonic (not to be confused with comma classic or motorway). I have also tried more expensive oils but for the GT the comma sonic seems to be the best combination of performance and price.

I would be a bit concerned about the oil light flickering, but as people have said above as long as it isn't on constantly then it gives time for the OP to think about what to do - as long as its not thrashed its unlikely to let go suddenly. For the moment the overheating issue would be my first job if I was the OP.