Freshly rebuilt engine - Oil light on!

Information that I have been given from lubrication engineers that I used to work with. Fully synthetic oils do not transfer heat as well as mineral oils, so your oil temperature will be lower. This means that the oil is not cooling the engine as well as it should. In industry they do not use synthetic oils for cooling applications. eg. large transformers

This is not my opinion, but what I was told by guys that went to university to learn about oils and greases.

(They also told me not to steal the very expensive molybdenum disulphide grease from work for my CVs as it would dry out because it wouldn't be worked hard enough)

 

I think they were telling porkies to protect their stocks.

 

Ok, well dont seem to be any further ahead at this point, mmmmmm, none for , none against.......

 

Hi guys, hopefully this is within topic but a colleague who has rebuilt other motors (not VWs) suggested that the first oil after the rebuild should be lighter (like a 10W-50) to get a good flow around the block, get everything lubricated, run a few 100k's gently for the run in and lubrication and then drop that oil (as you would anyway) for the post run-in oil change. Has anyone done that ... or think it would be worth doing ... on a 1.8/2l Type 4 motor?

 

I ran 'break in' oil on my engine (the one discussed in this thread.
Did not make a difference in oil pressure. The issue seems to have been related to case / bearing clearance, as once the case was replaced, the problem was gone.
At a guess, I think the problem was with the machine shop. I reckon that the engine builder took for granted that the machine shop's measurements were accurate and slapped it all together without checking clearances.