Diesel engine oil.

[Daniel]

Morning all. Need a professional opinion with regards to the above. A couple months ago I changed the oil for new Castrol Magnatec Diesel as well as the filter. Now the oil was recommended by Mitsubishi as being the one to use for both summer and winter (10w 40 semi-synthetic) However recently due to colder mornings, on start up it sounds like there's no oil pumping around! Really loud knocking from the engine tappets, much more than normal for a diesel. The previous oil (no idea who changed it or what was put in it) was much quieter and didn't knock that loud. So question is, should I really trust Mitsubishis recommendation or should I change it again for a thicker mineral oil as the engine's starting to age a bit?
Cheers.

[maff]

Isn't a thicker oil going to be worse on cold start-ups? I.e. take longer to thin out and move around freely?

[Daniel]

Isn't a thicker oil going to be worse on cold start-ups? I.e. take longer to thin out and move around freely?

Well if you go overboard with the viscosity then yes. But mine as it stands on cold starts sounds like there is zero oil flow for 30 seconds, then it quiets down. But the oil actually is pumping around.

[russ979]

Dan if i were you i would only go with exactly what is recommended by the main dealers. I know your truck is a good old fashioned cast iron diesel so viscosity shouldn`t be THAT critical unlike the newer stuff. An example is i have a clio dci here that has been serviced at an independent on time but with 10/40 semi instead of 5/40 and it had knocked the bottom end out by 81k! This is not the first i have come across.
The mornings are not that cold yet Dan, I can`t help but feel there might be something more than just oil choice at fault?
Good luck mate.

[stockcar]

have never liked Magnatec as its over-priced poor quality oil IMO...............