oil spec change

[Gaskell71]

Got a MK4 Mondeo 2.0tdci 140 and was planning on changing my oil spec from 5w-30 A5/B5 oil to 0w-30 A5/B5 oil, I do tend to do a lot of cold engine driving with short runs. 

So was thinking this would offer better engine protection while still being the correct weight oil for the eninge?  Would that cause any issues with the engine?

[Milkman]

Personally I would not change from what is recommended by the manufacturer, a straight 30W will stay thicker for longer and defeat the object, if you're worried about just doing short journeys just let the engine get up to normal running temperature before you drive off.

[Gaskell71]

God no, not a straight SAE30 oil the operating range would be way too narrow.  I believe or have the understanding that a SAE 0w30 would have the same operating spec as a 5w30 but is more viscose at cold engine temps and in colder weather. 

Being more viscose on a cold engine which I have most of the week not even getting water temp to the first line on the gauge might be beneficial.  anyhow may just stick with recommend 5w30 oil type. 🤷

Quote from moble1 website that got me thinking about it in the first place

""A 0W-30 low viscosity oil can be used where a 5W-30 or 10W-30 is recommended. Switching to a Mobil™ 0W-30 motor oil can help improve fuel economy because of the lower friction properties offered by this full synthetic formulation.

We offer Mobil 1™ Advanced Fuel Economy 0W-30, which is dexos1™ certified. General Motors recommends dexos1 certified motor oils for all 2011 or newer vehicles.""