If its a TMP,, which is what I have on my 4107, the recomended is SAE 20. Apparently multigrade foams, and certainly not EP type oils (EP80/90 as you may use in a car 'box).
I think I got my SAE 20 from Miller Oils..otherwise it can be a bit tricky to track down.
also on the TMP its very important to check the nipples on the raw water cooling.
the 2 bronze nipples on the aft end, i changed mine to Zinc ones supplied by Perkins. the copper external inter-connecting pipes married to the TMP aluminium casting tend to "Fizz" a bit.
it cost me £1100.00 6 yrs ago /forums/images/graemlins/mad.gif /forums/images/graemlins/mad.gif /forums/images/graemlins/mad.gif
Good point about the 'raw water' inlet/outlet connectors.
1 of mine is 'fizzing' and is due to be changed this winter ..the chap at TMP said that it was due to it being zinc and served as an anode...but maybe from what you say its around the other way.
I understand it can be tricky to extract these little luggers, once again the chap at TMP suggested that the easiest way was to take a hacksaw blade (out of the saw frame of course) and poke it up the inlet and saw the connector on both sides then extract the 2 halves.
The reason I mentioned about oil foaming is that after an engine run a couple of years ago I checked the 'main box' oil level and was horrified to find what i thought was emulsified oil (oil water mix).... I drained off a sample to take a closer look and noticed that after a while the foam reduced and the oil went back to normal.. big relief.. when i checked with TMP they mentioned the point about multigrades and foam.
How much did you pay for your nipples? (if you don't mind me asking)