Millers Semi Synthetic....

[bcmc33]

If the level of oil in the oil pan/sump is too high the crankshaft & con-rod big ends will make contact with the oil (punching/thrashing) which imparts energy = heat into the oil which can cause a dramatic rise in temperature.

That's why I fit a windage tray in the sump.
However, I reckon you would need over 8 litres of oil for the crank & con-rod big ends to make contact with the oil surface as you suggest.

My experience regarding oil temperature is non-existent - so what is the consensus for the oil temperature in a normal working Twink?

[GrUmPyBoDgEr]

If the level of oil in the oil pan/sump is too high the crankshaft & con-rod big ends will make contact with the oil (punching/thrashing) which imparts energy = heat into the oil which can cause a dramatic rise in temperature.

That's why I fit a windage tray in the sump.
However, I reckon you would need over 8 litres of oil for the crank & con-rod big ends to make contact with the oil surface as you suggest.

My experience regarding oil temperature is non-existent - so what is the consensus for the oil temperature in a normal working Twink?

Phew Brian,
8 Litres sounds a bit optimistic.
I wonder how much the racers put in their engines?
I've seen one such candidate who "always puts more in to reduce surge" but after a race the engine bay was covered in oil that the engine had disposed of via the breathers; an obvious sign of crank thrashing & subsequent foaming/frothing.
Thrashing not only causes higher temperature but also a big drop off in power at higher revs; something that racers don't really want to happen.
I wrote that 140?C is very high but not critical.
I'm not certain about what "semi-synthetics" are capable of but the problem with mineral oils is that they quickly start to oxidise at about 150?C
Fully synthetics will cope with 150?C OK & take short periods of 165?C before that happens.
Any degradation from the full synthetic i.e. adding mineral oil immediately drops the critical temperature to 150?C so I "assume" that will be the case for semi-synthetics.

Cheers
John

[JJDraper]

The oil temp sender is fitted in the sump and seems to be accurate. The observed climb in temp really is at sustained revs (4-5k), i.e 80-90mph for hour after hour; also some of the long mountain passes when you seem to be going up for ever. Normal running oil temp seems to be 90-120DegC, but it takes a long time to get there - 10 miles or more, even at this time of year. I don't think overfilling is an issue as the engine doesn't chuck out any oil. In an oil change it seems to take around 4 litres to re-fill (Brian - did you mean pints??). Very little oil use in service, maybe half a litre between changes. The oil temp seems to respond to 'pressing on' far more than coolant.

The coolant temperature stays pretty static at 90, or middle of the gauge at speed. Coolant temp can rise on the long climbs, but when the fan kicks, in it brings the coolant temp into line, with no bother. Interesting that coolant temperature also rises at slower speeds - 50-60mph, just pootling along. Probably the drop in air speed across the radiator, until the fan kicks in.

Fitting the oil temp gauge was just for interest on the +2, to replace the ambient temp gauge, which pretty much tells you what you know anyway! If I hadn't fitted it, I wouldn't be worrying about oil temp! Ignorance can be bliss..

Jeremy
thinking about an oil cooler!

[69S4]

The oil temp sender is fitted in the sump and seems to be accurate. The observed climb in temp really is at sustained revs (4-5k), i.e 80-90mph for hour after hour; also some of the long mountain passes when you seem to be going up for ever. Normal running oil temp seems to be 90-120DegC, but it takes a long time to get there - 10 miles or more, even at this time of year. I don't think overfilling is an issue as the engine doesn't chuck out any oil. In an oil change it seems to take around 4 litres to re-fill (Brian - did you mean pints??). Very little oil use in service, maybe half a litre between changes. The oil temp seems to respond to 'pressing on' far more than coolant.

Jeremy
thinking about an oil cooler!

I've had an oil temp gauge in my S4 since the 80's, also with the sender in the sump (or at least I did until two weeks ago when the capillary line got snapped off - anyone know if they can be repaired?) and my oil temp is much much lower - round about 55-60DegC on a normal run. I do have an oil cooler fitted (again, since the 80's) but the oil temp is much the same whether it's blanked off (usually wrapped in something) or not. It will rise if I'm running the car hard - eg mountain passes, but I don't think I've ever seen 120DegC on the gauge.

Steady state water temp is usually about 88-90DegC and in traffic / mountain passes that will remain in the low 90's as the oil temp increases. When the oil temp eventually matches the water temp they then go up in step and about 110DegC is my bail-out point, the time at which I either ease off or switch off. In traffic though, with the std electric fan running, it could take well over an hour to get to that stage.

I've just been using std 20-50 mineral oil in the car, the same sort of stuff it's always had. The thought of changing to some more modern formulation had fleetingly crossed my mind but the price differential soon put paid to that . Oil consumption on a 2000 mile trip through France last year was about 2/3 litre (based on the mess it was about 1/2 litre used by the engine and the rest leaked out)

[bcmc33]

For my education I contacted Millers regarding temperature and received the following reply:

It is not uncommon for Millers full synthetic competition products to reach over 130 deg C, semi synth would not tolerate that temp for prolonged periods of time.
Mike Fenton
Technical Services Manager
Millers Oils Ltd

[GrUmPyBoDgEr]

I think that it's worthwhile noting that very high oil temperatures are achieved by using high engine speeds for prolonged periods.
For many years I had to do high speed testing on car lubrication systems.
High speed banked tracks such as the one in Nardo, southern Italy or the Uniroyal facility in south east Texas or even BMW's own facility in Miramas, south of France.
All of those tracks are up to around 5 miles per lap.
Part of my job was to drive full tilt, loud pedal on the floor until the engine oil temperature stopped rising.
Generally speaking that occurred after about 12 Laps.
If anything caused me to take my foot off the accelerator for only just a moment the oil temperature would drop dramatically & that meant doing more laps at horrifyingly high speeds & high ambient temperatures (often without air-con') in order to obtain the results I needed.
I doubt very much that there is any road anywhere where such prolonged high speed could be maintained.
My point being is that measured temperatures of say 140?C will only be peaks that are present for only a very short period & should not cause concern if you know that you have good oil in your engine.

Cheers
John