The Fordson Tractor Pages Forum

Some may recall I used some 30wt oil on my last change on our '55 Major.
It has been so cold and slow starting I decided to go back to 15-40.
Since I've done the two changes the oil on dipstick is staying very clean, which concerns me. All the diesels I own the oil gets dark right away. Oil pressure comes up soon after start and stays at 40 under load, 25 at idle.
Maybe due to the oil be changed so quickly?
I really would not have expected it to be so clean as both drains were done cold, which I have never done before.

Probably the short oil change interval is the answer - the oil discolours due to carbon and other bi-products of combustion being washed down by the detergent oil circulating round. Particles above a certain size are taken out by the paper filter but extreme fine particles will pass through the filter and remain in the oil causing discolouration without doing any damage to the engine.
You would do better to drain the oil when it is hot after the engine has been working, this will help to bring out any residues in the bottom of the sump.
With regard to oil viscosities, after the engine has run and the oil is hot all grades of oil will have similar flow properties and similar lubrication properties, that was one of the reasons behind the introduction of and the benefits of multi-grade oils.

If the oil stays clean it will survive better and give higher quality lubrication, after our changes we've had to do quite a few hours work before the oil got dirty and then it took about 20 hours to get black again. The more you change the oil the cleaner and healthier your engine will be.
Agree 100% shepp.
Sandy

Alright, thanks to you both. I was concerned that the oil was not circulating. With the cold drain I was really surprised to see it so clean.
On my Cummins the oil is darker after a quick warmup to check for leaks post oil and filter change. Maybe more places for oil to remain?

Possibly, but you might also notice that a less cared for engine will be dirtier in any case, both Billy and Davie show red oxide paint through the oil filler, whereas Super Billy is still black in spite of many hours hard cleaning and no running since that. If the oil wasn't circulating you'd find a dry rocker shaft and maybe low oil pressure, 25 psi at idle is a bit on the low side, but just keep an eye on it, anything below 20 psi is a cause for concern, but if you keep everything clean you should be ok for now.
Sandy