E: Engine Oil Viscosity

[Matty]

Hi
Just had a chat with Morris oil technical guy about their classic Golden Film 20/50 which I use and he says it is fine for air cooled engines like the Vincent and should be OK for twice my annual mileage of around 4,000.
However he also said that if run in an engine with no oil filter (the Comet has one) it would be safer to change it more often - didn't give a figure, but said the detergency which holds the sludge in suspension is now much less than it used to be, particularly for oils designed to use in Classic machines.
He also said that the old problem with polymers degrading had also been greatly reduced now so the oil stays thick for much longer.
He was understandably reluctant to give figures for these various factors of life etc. over the phone, but said that most of the straight/multigrade problems had been fixed in the last 10 years or so.
The running time for the Aero engines above seems to imply by the way that all is well for the cams and followers up to 50 hours which would seem to be at least 1500 miles on a bike.
I have not done so yet, but he suggested that I read through Morriss's brochure on the subject for more details.
PS I had said I used Millers oil but in fact it was Morris oil - must be a small onset of altzimers !!
Matty

 

[John Cone]

With regular oil changes due to doing short journeys i use ADSA 20/50

 

[Matty]

Have looked at the Morris site which is at :-
https://www.morrislubricants.co.uk/custom/upload/File-1458212983.pdf

An extract of their information is below :-

GOLDEN FILM 20W-50
Classic Motor Oil
Description:
Golden Film SAE 20W-50 Classic Motor Oil is specialist high quality, low detergent/dispersant multigrade lubricant. This oil is suitable for use in naturally aspirated four stroke petrol and diesel engines.
Applications:
Golden Film SAE 20W-50 Classic Motor Oil is recommended for use in veteran, classic and vintage cars, motorcycles, commercial vehicles and tractors, where engine design and tolerances prohibit the use of modern high additive level oils. Golden Film SAE 20W-50 Classic Motor Oil is a low dispersant oil and allows any solid contaminants to drop harmlessly into the sump. This is an important feature where early methods of oil filtration, such as mesh gauzes or strainers are fitted.
The multigrade properties of Golden Film SAE 20W-50 provide improved cold start circulation whilst maintaining good working oil pressure.

I think that the filter fitted to our Vincents should make this oil very suitable for us and should result in us only having to replace the oil and filter at quite infrequent intervals of say around 6000 miles.
Matty

 

[mercurycrest]

Has anyone had experience with Dynolite brand oils for Vintage vehicles? They seem to offer a good range.
Cheers, John

 

[Tommy Shields]

I just thought I might mention about different grades of oil and the effects it can have on our engines. After the rebuild of my Rapide last year, and after the first 500 miles I changed the oil and filter. Ordinarily I have mostly used a 20w/50 mineral oil, but this time I opted to use a Penrite 20w/60 that had added Zinc for better protection of the cams and followers, so I gave it a try. Since the rebuild I have noticed that the engine has been more difficult to start, but the main change had in reality been the change of cams, from original Mk 3's to some type of Mk 2, I say that because I have no idea as to their origin, Only that their specs match most other Mk 2 cams giving about 0.385" lift at the valves. With this newer oil I had chosen, I noticed that it is definitely thicker, and it appeared to me that when kicking the engine over that it felt as though it had wet sumped, as I could feel the extra drag as the engine tried to rotate. The only thing was, that if I removed the sump plug that only about 150 Ml's of oil would drain out, so hardly a wet sumping problem. So with the new engine at about 1200 Miles now last Thursday I changed the oil/filter, and used a 15w/40 mineral oil for Diesel engines. Started the engine after I first primed all the oil ways and filter chamber, and on the Saturday the wife and I headed off for a local bike rally where we clocked up about 100 miles or more on the Saturday stopping here and there for a toilet stop and for lunch. I guess over the weekend I must have started the engine 7 or 8 times, and it basically started first kick every time, and I noticed how much easier the engine spun over considerably quicker than with the heavier oil. It is surprising how much extra drag is imparted within all the roller races and to some extent from the piston skirts to the cylinder walls. Before this my level of frustration was climbing rapidly as nothing is more annoying than trying to start an engine on a newly rebuilt bike that you and everyone else around you knows should not be that difficult to start. After last weekend, I could not have been happier with how it started, because when it is running, it really goes very well. Interesting results.............

Hi Dave
Have you drained the sump with the thinner oil (15/40)? If so, how much came out? I'm asking because I don't think my oil pump is managing to return all the oil to the tank. I live in Scotland - a wee bit colder and so the oil remains more viscous. If I drain the sump after a period of use I'm getting about 250ml. The pump has been checked and is fine. I'm considering using thinner oil like yourself.
Thanks
Tommy

 

[davidd]

Tommy,

It is a little difficult for me to answer because it is a racing bike that is being tested. 250ml does not sound excessive. I used to run the oil for two meets, but there is so much metal in it I went to changing it every meet. I would have some oil in the sump when I did not change it every meet.

David Tompkins first alerted me to the lower viscosity issue and I was reminded by Martyn that Mr. Irving seemed inclined to lower viscosity oils. We have been testing lower viscosity oils that have incredibly high wear resistance (best for flat tappets). Interestingly, there are no high ZDDP oils that test well enough to get high marks in the high film strength tests (none in the top ten, I believe). The oils that are being tested are in the 5W30 range.

So far the oil has shown higher temps in the UFM than the higher viscosity oils. To me, this a good sign because the tank oil temperature has always been remarkably low (except at top end speeds).

I was thinking that your flywheel must be to slippery for oil to stick to it if you have too much oil in the sump! The sump, being in two parts, carries the oil via the flywheel, or flywheel windage, into the second sump just clear of the flywheel. The oil pools in this second chamber until the scavenge side of the pump sends it up toward the heads on its way to the ufm.

I added a drain plug to this second sump, so I could remove the oil in this chamber. I had a situation where I had trouble with the old contaminated oil in this chamber ruining the clean oil. It was a rare situation, but because it was a Comet the drain plug was easy to install. In normal use, I would expect the scavenge pump to drain this chamber very quickly.

Personally, I don't worry much about the oil in the sump. I drain it and add a little more if it is low in the tank. The old pumps that are still good let as much oil by as the new pumps, otherwise there would be lots of new oil pumps sticking in their bores.

David