Morris Minor Owners Club

With this hot weather its a fine time to see the max oil temps we get, so I'd like anyone who's got a oil temperature gauge to say what they're seeing.
For me, a few days ago in an air temp of 20-22C cruising at 50-55 mph along the A303/M3, after about 25 miles both the water and oils stabilized at 180F (82C). Returning home at 60-65 mph water and oil stabilized at 190F (88C) peaking on a climb along the A343 with water at 195F (91C) and the oil at 200F (93C). When I got home the oil was on MIN level.

Today in an air temp of 28-30C on a short 12 mile journey (6 miles there and back) and with the oil level at MAX, I got the water up to 194F (90C) and the oil to 178F (81C).

Also I'd like your ideas of the right temps we should aim at. My reading of the interweb suggests a range of 80-105C as about right which seems from my several years experience with a gauge just about what my 1098 does. But in winter I'm lucky to get any where near 60-70C, most of the problem being to get it warm enough. What's your experience? (Note, while 1275, racing, etc experience is interesting I'm seeking info on standard engines to find the norm.)
Regards, MikeNash.

It will depend what thermostat you are running - in winter anyway! But short winter journeys will never get the oil hot enough - hence the 'mayo' often found inside the rocker cover. The Metro Turbo had an interesting oil/water heat exchanger to make sure the oil was warm enough in winter - and cool enough in summer. I suspect v few of us have oil temp gauges fitted.......

Yes, I should have added that I have a 89C thermostat fitted and my water temp is read from the heater supply pipe (its always on), the latter 'cos my gauge pipe is very short and the normal point at which the temperature is usually measured i.e. beneath the thermostat, has an internal bulge in the head casting that prevents the sensor bulb being screwed in. Also, I've done the obvious checks on the gauges with hot water and a reliable thermometer, and finally the road speeds are checked against GPS.
And I'm running on Wilkinson's 20/50 oil (at £9 a gallon). Regards, MikeNash.

I suggest that's a bit too high thermostat for (this!) summer weather...... Excellent in winter - but I would urgently go for 74 degree stat this summer. What's the oil pressure when fully hot at 50 mph??

Oil pressure at 50 mph is (from memory) the full 60 psi; I'll check this is right later. At idle and a temp of 81C the oil pressure is 20 psi, so I'm happy on that front. (Its the engine I bought from you!) Indeed, with such good oil pressure at fairly high temps, I'm thinking of going back to the Morris recommendation of 30 grade oil - using a modern one of course (5/30?)
Regarding the thermostat I'm happy with the 89C opening and have run it for several years often finding, of course, that it doesn't open at all in winter, the block being enough of a radiator itself. And running with the usual 4 psi radiator cap which gives a raised water boiling point of 106C (? - I've not got my steam tables at hand) I've still got some 15C "headroom" before I loose water. And in practice I never do.
But my focus in this thread is oil temps, and since oil temperature gauges are rarely fitted to standard road goers its only via the wide net of this club site that I'm likely to find anyone else who's fitted one and hear of their experience. Any takers?
Regards, MikeN.

Worry more about the oil pressure - that 60 psi is fine then - I would NOT go down to 5W30 oil - these engines were never designed for that and oil consumption will increase horrribly. Stay with the 20W50 (Wilco is fine) at least in summer. If you use the car extensively in winter - perhaps 10W40 would be ok then.

I don't think many Morris Minor owners will have an oil temp gauge with a standard engine, as it isn't something to worry about. It is more of a problem on the gearbox-in-sump A Series and Flat Four engines like the Jowett Jav/Jup, where the horizontally opposed cylinders mean the sump misses out on much side cooling.

Unless the engine is in first rate condition, I'd advise against even a 10w40, as this will rapidly disappear on a high speed run. If the car is used for pottering about, however, it could work well.

The 20W50 is thinner when cold than the original specified Castrol XL 30 SAE. It's perfect for all A series -certainly in summer.

I can't help with a standard engine, but our 1380 has an 82°C thermostat year round and the MG Metro water cooled oil cooler that Roy mentioned earlier in the thread. Pottering around town the oil temperature is around 70/80°C and on the motorway gets up to ~90/100°C in cool weather and 110°C in weather like we are having now (~30°C). On a track day it might go up to 125°C. The oil is Castrol Edge full synthetic 10W/60 and the oil pressures are very similar to yours at all temperatures - it is really only the idle pressure that seems to vary with temperature a bit, the normal running is 60/70 lbf/in2 almost no matter what.

With the design clearances of an A-Series engine, I would definitely not use anything less than a 20W/50 oil year round. Good modern oils are the main reason that engines last much longer than they used to - for me not an area to compromise at all.

I have a semi std engine, with a 1275 head, and a gauge. The temp sender is fitted in the supply gallery to the pump, recording the temp of oil coming from the sump. The engine has had 20,000 miles since a full recondition.The thermostat is 88 deg. Oil pressure is as you would expect. Oil is either 10-40 or 20-50.
It takes a while to get the oil up to full temperature, 5 to 10 miles depending on the outside temp. Water temp is a lot quicker to get to normal. I don't ask a lot of the car until the engine is fully warmed up, oil and water.
The stabilized oil temp varies from 95 to 115 depending on how the car is being driven. At constant speed, 100kph (NZ speed limit), the oil temp will be 100 to 105, water temp 85 -90(outside 10 - 20 deg,) and will climb to 115 - 120 oil temp, 90 - 95 water temp when it is hotter (high 30s). Easing off for a little while drops the oil temp.

That's quite hot for oil - assuming the gauge is accurate. But if the pressure holds up even on the 30 degree days - I guess it's ok! Perhaps it's just as well I don't know my oil temperature - it's an identical spec engine......

assuming the gauge is accurate

Yup - been there!

I fitted the Smiths electric oil temp gauge at the same time as the 1380 engine and the readings looked much as expected. After various 'upgrades' to the engine the running oil temperature appeared to increase over a period of maybe 10 years, and at times on a track day would be around 135/140°C, so I thought I would have to fit a 'proper' oil cooler to replace the Metro water cooled sandwich plate.

Not much room for a neat location, even with all the space in a Minor engine compartment, so I bought a long, thin oil cooler from a Saab that would fit across in front of the radiator, but above the starting handle line.

Before fitting it and very much more in hope than expectation, I tried a new voltage stabiliser, but that gave the same readings, so as a final attempt I tried the oil temp sensor in boiling water and found it read consistently between 10°C & 15°C high at 100°C. So after a quick gauge head recalibration, no need for more oil cooling! That was around 3 years ago and all seems OK still.

I have checked the gauge against a known accurate external thermometer. Not exact, but within 2 deg.
The oil pressure on those really hot days held up ok. On a normal day, motor fully warmed up, at 100 kph = 60 psi, 85 deg water, 105 deg oil.
This may be of some interest - http://www.minimania.com/classic-mini-c ... fm?id=1005

I'm surprised the oil is going over 100 degrees - Minis are very different - because the gears and the final drive are all churning up the oil and adding even more heat! Certainly the sump is aluminium and ribbed - possibly to aid cooling although I suspect more for strength.....and I always ran oil coolers on my Minis. Indeed I ran a small oil cooler on my early 948 rally Minor - it (and a crank damper) was the only way I could hold the engine together!

Thank you gentlemen, esp Roni and Mr Islip; I feel happier now and am less concerned on seeing the oil occasionally peak at 210F (i.e. 98-99C. My gauges are the ancient Smiths capillary type measuring in Fahrenheit and reading in 5 degree steps that I've checked with a reliable mercury thermometer. Translated to Centigrade and interpolated between steps it gives me values with confidence within about 1-2 degrees Centigrade.) This max temp has only been seen when motorway cruising for long spells (1-2 hours) at 60-65 mph (true) with a full load with an ancient motor which drank and spewed so much oil that I was often approaching the "MIN" mark. (Max pressure with Asda 20/50 then fell to 42 psi, but the motor was always reliable.) Most advice on the interweb is in the range 80-110C which sits well with the above Moggie experience (except for aircooled motorcycle engines, e.g Harleys and Ariel Square Fours - a different breed! But as an aside "Cockpit - An Illustrated History of WWII aircraft Interiors" by D Nigboer &D Patterson shows several oil temp gauges with pointers showing just this range.)

I'd like to turn your attention to your views on the minimum temperatures you like to see. The above 80C seems about it based on the idea that above this temp condensation is rapidly evaporated away. There's no evidence I can find to support this though, so the figure might be based on just arm waving and gut feelings. I suppose one can say that if you've reached a bulk oil temp of 80C then somewhere like the underside of pistons you'll get over 100C and so boil the water off at least at that those places. However if 80C is the target for a minimum oil temp then outside of motorway running I rarely see it in winter or spring. With my 89C water thermostat and careful radiator blanking I'm lucky to get above 70C even with long drives. No wonder we get mayo in the rocker cover!
What are your views? Regards, MikeN.

after about 25 miles both the water and oils stabilized at 180F (82C)

Sounds fine to me, I'd be happy to see that if I had gauges fitted.
Are you getting mayo in the rocker box?
More blow by at the rings will mean more combustion by-products in the engine and H2O is a major by-product.
Someone made a rocker box cosy that seemed to sort mayo out or at least put it out of sight somewhere.

Make a 'cozy' for the sump in winter???

That would be sumptuous

Groan.....

Reducing blow-by or improving crankcase ventilation are what I had in mind, but the sumptuous sump cosy sounds like a real winner "you're hired!"