sorry I know (have read) this may have been done to death.... but I'm confused....

15 plate Ford Focus 1.5tdci (titanium)

some oil recommendations are 5W-30 and at some point recently the change was made to 0W-30

I did the last oil change nearly a year ago and used Castrol magnatic 0W-30 stop start.

but I've noticed that the vehicle seems more reluctant to actually stop start than it was before. (I am a second owner, so have no idea what was used previously or if the oil would have an effect on stop/start (I know the engine needs to be up to temperature too, and suspect it doesn't like going into stop start at lower ambient air temperature)

 

I am also very confused about the recommended sulphur content of the oil..... C1, C2 or C3....

it appears that Castrol 0W-30 or 0W-35 is generally C2.... but C2 and C3 are actually the same as except the hths is slightly different

https://www.opieoils.co.uk/t-acea-car-engine-oils-specification-explained.aspx

 

how bad would using 5W-30 be against 0W-30?

 

(I have another motive..... I have another large capacity high performance (petrol, non Cat) GM engine which requires 5W-30.... so I was considering bulk buying 5W-30 and was considering C3 or C2/C3 non Castrol as I did not want to be had on cost with Castrol (the other engine requires Dexos 2 spec and is a very expensive high performance >500 hp @ 7000rpm engine).... their recommendation has changed to 0w-40 of late but have a preference for mobil1

day car (motorway mile muncher) focus... hobby car (still under build)

 

 

 

 

Genuine Ford Castrol 0W30 Oil 5 LITRE Magnatec Professional eBay item number:184217364026

is the oil you should be using,  the start stop is just a gimmick they put on the label a few years ago.

your owners manual should tell you the grade of oil also. takes nearly 4ltrs to fill up after oil and filter change.

I use Napa engine oils now on my Mondeo 2.0tdci that requires 0w30 . It's formulated to ford specs. And it's only £26 for 5 litres napa is a brand name of valvoline USA. 

 

thanks.... I never got an owner's manual when I bought the car previous owner stripped it clean (sat nav SD was missing too). hence the dopey question

You can always download or view online the owners manual from the ford website 😉

thanks very much I didn't know they could be downloaded

oil is 0W-30 C2 (it was the C1, C2, C3 or C4 that was confusing me the most)

at least I put the right oil in it last time.

 

thanks all

On a new Mk4 - at least - S/S not working might also be a case with worn battery or faulty BMS sensor. Focus has got some hiccups with those, some are reporting that even with latest software upgrades and replaced BMS that's supposed to fix the issue, the battery does not keep charge properly causing, among other things, S/S to deactivate.

My next car won't be a Ford.