Which Oil is Best ?

[Sam Christie]

Please forgive me for asking such a basic question which sounds very familiar but -

Which oil is best for a thoroughly clean completey rebuilt OHC Minor/M-type engine ?

My engine has been fitted with a modern oil filter - does this influence the choice ?

[chris lambert]

Sam,
My saloon engine also has a modern filter fitted. I have used a Morris Oils (co-incidence) multigrade since its rebuild and it is fine. I am away from home at the moment, so can't check, but think it is a 20/50. All modern oils have got wonderful 'longer life' qualities and the synthetic oil in my BMW is changed once every 20k+ miles. I am not sure how a synthetic would perform in our ancient engines. Would we have any oil pressure as when hot the engine oil has zero viscosity apparently? Any oil technologists about?
Chris

[Trevor Wilkinson]

Not an answer to your question but I thought that I would have my say. I am running my SV minor on a 10/40 semi synthetic and also have a modern oil filter. I maintain good oil pressure when hot. As far as I am aware there is no problem to using modern oils providing that a modern oil filter is used, modern oils are designed to keep any dirt in suspension in the oil to be filtered out, older oils allowed the dirt to settle in the bottom of the sump (sludge). It would not be ideal to circulate the dirty oil around the engine as would happen without a filter.

[Toby]

I use a nondetergent single grade for my sv, PJ, as I have no idea how clean the insides are and there is no filter, also it means I can use 50grade in summer to help with the hot engine. NEVER use flushing oil, it frees up trapped dirt and increases tolerances and thins the new oil after flushing. Old style oils are fine if you do regular oil changes which of course would have been the case with summer and winter grades, any oil should be changed after winter laying up. I now have a new engine for YG (Algie) and have put in the same oil for the initial start up, however I'm considering fitting a filter on the sump pipe, I have an inline on my bike but its on the return to avoid oil starvation, would this work on the feed pipe or would it restrict the flow???

[Trevor Wilkinson]

Hi Toby
I have an oil filter on the pipe from sump to oil pump, I have not had any starvation problems but after oil and filter changes it does take a long time to get the filter and pipes primed. after this there is no problem.

[DF9053]

Hi Sam,

There was a debate some time ago about oil in Minor engines. DF had Castrol R which is a 40 grade, many people swear by this oil many others like the smell! However you can't mix this with anything else so it can be a problem if you run low on a journey, it also costs quite a bit.

After DF's rebuild I asked around and there are two schools of thought. Firstly stick with the straight 30 grade, low or no detergent. As the posts above say old oil design is to drop sediment in the sump as there was limited filtration. However the other schools thinks that a low detergent classic multi grade is fine, people have been running Minors on this for years with no ill effects. I now run DF on Halfords Classic 20/50, I would have thought that as you have an oil filter this is a good option. I get 120 psi at start up, droping to 60 psi at hot tick over maybe a bit lower. 30mph in top sees 100 psi at all temperatures. I also change the oil every 700 miles or so, in the Minor you get two changes from a gallon so its not too expensive - certainly cheaper than new bearings

Could you email me details of the filter set up, with only 4 pints of sump oil in a Minor it sounds a good idea!
Cheers
Jeremy

[halbe]

All thought not a Minor I use Duckhams 20/50 in the Aston's engine and did so for the last 30 years without problems.
The engine also has an ohc engine but has a dry-sump lubrication system.
The oil tank holds about 11 lts of oil ( more than 2 gallons) so oiltemp. is never a problem.


Halbe

[prharris25]

I used Duckhams 20/50 for years, despite awful warnings what it would do to the cork clutches in my 10/4, Bullnose and Flatnose cars...never had any problem and oil pressure good.
Now use Halfords Classic 20/50 and , if anything, find it holds the pressure when hot slightly better.

[Sam Christie]

It seems Duckham's is not new to the OHC engine.

A friend with an M-type of astonishing originality which included documents and tool kit also had a tin for engine oil which appeared to have genuinely come in 1929 with the new car,clipped to a bracket in the tail. The message on the tin read -

For "Safety Fast" Confidence
Duckham's
New Process
N.P5
Oil
Officially Recommended
By
The MGCar
Company Limited

What, I wonder, was Duckham's N.P5 Oil ?

Sam

[Ken Martin]

I contacted several oil companies a couple of years ago for advice and found that they all recommend straight 50 grade oil unless a modern type filter is fitted. There is much info on the oil company web sites. However on consideration I ignored the advice as I didn't like the idea of muck potentially accumalating in the sump.

If modern shell bearings are fitted (to new type rods - as often used with a modern Pheonix crank) then fitting a modern oil filter is essential. This has to be done properly in the proven MG way - a modern filter shouldn't be fitted into the original housing. The original white metal bearings absorb small debris - the rest is suposedly collected by the 'filter'.

I still use the original 'filter' arrangement and always use 20/50 grade oil - usually Morris Oil actually. I have a 1 gallon capacity MG Midget sump and change the oil at least every 1000 miles.

Ken

[Highlander]

I was interested in Jeremy's comments on oil pressures. I rebuilt my 1932 sv engine two years ago because I ran a big end due to too low oil pressure. I keep on about my hight but I cannot see the oil pressure guage without bending double and because I have oil pressure I thought I was OK. WRONG. (it was 10 psi hot!!!!) On start up when rebuilt the oild pressure was still not good but better then before. I again rebuilt the oil pump, new spring, new ball bearing etc, lapping the ball in and pressure was very much better - but - The guage goes off the clock when cold. When very, very hot and flat out, for me that is 40 mph, I get 40 psi, again when very hot and SLOW tickover it is almost zero. I have a one gallon sump (just a 4 pint sump with an added piece wealded in) and I also use Halfords Classic 20/50. I change the oil every 1000 miles and I change it into a white enamel bowl and there is NO deposits of white metal. I just soldier on - am I right? Filled up today and still only doing just over 30 mph. With Molly on board I notice the difference when pulling uphill - I am changing down mjuch earlier and more often. Keep the info rolling in, Highlander (Alister)

[1936morriseight]

Looking in a 1930's Commercial Motor Catalogue, Duckham's "Adcoidised N.P." Motor Oils - specified for Rolls-Royce, Austin, MG, Riley, Standard and Hillman were as follows:

N.P. 2. - S.A.E. 30 medium
N.P. 3. - S.A.E. 40 medium heavy
N.P. 5. - S.A.E. 50 heavy
N.P. X. - S.A.E. 20 thin (winter)
N.P. XX. - S.A.E. 30 thin (summer)

At this time Duckham's were also marketing their "Adcoids" Wear-Cure Tablets in boxes of 12 tablets for 1 shilling - were these tablets added to the oil or the petrol?

[DF9053]

The oil pressure on side valve engines is a lot lower than the ohc ones, I can sure others will have more specific details but I don't think 40psi is too bad for one of these engines.

cheers
Jeremy

[chris lambert]

A couple of observations on oil. I have just changed the oil in VJ from a straight SAE 40 Penrite oil to Castrol Magnatec 15/40 Semi Synthetic. (I am using Morris Oil 20/50 in OU 6930) Firstly the engine gets upto temperature much quicker and despite the cloying qualities of cold 140 in the gearbox and diff, pulls much better and earlier than before. Secondly, oil pressure under load is not affected at all, but now drops to 45 psi on tickover. When running on Penrite, oil pressure never dropped below 70psi.
A final observation, is that after a winter with just a couple of runs there is a tendency for condensation to form within the block, particularly if your car is not kept at a constant temp in a heated garage (neither of mine are!) and the winter has large variances in temp. A rapid rise in temperature following a period of cold weather will leave the outside of your block coverered in condensation. I have noticed this many times.The same process will be occuring on the inside. Your first long run could cause you some concern as this condensed water emulsifies with the oil and shows as a white emulsion in the oil filler. This has occurred in both my cars each year, although it is nowhere near as noticeable in the car that is kept in the wooden garage, as opposed to the car kept in the garage with a concrete floor, breeze block and brick walls. It is definitely a signal to change the oil pronto. Once done, it never appears again until the start of the following years season. By the way the same process takes place inside the gearbox and diff.
Chris

[Highlander]

I have just returned from the pub meet at Bramshill. A round trip of 100 miles. I went to the pub across country as I do not like holding everyone else up. What with traffic lights and roundabouts it was a pain. Oil pressure when very hot was just between 20 and 30pqi and slow tickover nothing. I came home the quick way and held 35 - 40 mph for one and a half hours. Oild pressure just the same. The minor remained quiet and no tappety noise. I uses Duckhams 20.50. At the meet I mentioned I have two oil pumps with deeper gears (morris 8 ?). The suggerstion is that I try one of these as I may get better pressure. Engine rebuild 18 month ago and pressure never been any better. Off the clock when cold and stays high until very hot. Need I worry? Highlander.