Hello,

I am having currently a dillema with my 2004 STR it's suggested to use 5W-30 API SL/EC and ILSAC GF-3 which falls in the range of A5/B5 ( I currently use Shell Helix Ultra Professional 5W-30 A5/B5) but the same engine but on the XF 2008 SV8 "suggest to use V8 Petrol engines Use only Castrol 5W-20 engine oil meeting specification WSS M2C925-A". Thing is I am currently thinking to put in my STR 2004 SHELL Helix Ultra Professional AF 5W-20 which is A1/B1, which would be the correct oil since I have read that the 4.2 V8 Supercharged engines are dreaded by Timing Chain issues since the oil is to thick at 5W-30 and it doesn't have enough time to circulate faster to the timing chain, hence the 5W-30 swap, I live in Romania which is a normal climate, not to hot, not to cold. Have you faced the same issue? I honestly have no idea what to use and I do not want to bust the engine since it has clocked only 150.000 km on it.

The engine sounds a bit rough at a cold start with the 5W-30.

 

4.2s don’t have chain issues lol.

use acea a3/b4. they stepped down to a5/b5 and then 5w20 for fuel economy reasons

 

Main issue is that I cannot find 5W-30 A3/B4 on the market, only spec that is close to A3/B4 is C3 in terms of HTHS


The Shell Oil Configurator and Castrol Oil Configurator suggest me 5W-30 A5/B5 (Which I might think it's marketing scheme for their products)

 

use 5w40 then. 5w40 and 5w30 a3 are both close in hths

 

Yea I think I will stay at 5W-30, maybe next year I will give it a go with a 0W-30. But I highly doubt I will try to pour 5W-40 since it's to thick.

 

I definitely would not recommend doing this. Stay with the spec. If the chain really makes a lot of noise, consider replacing timing chain, guides and tensioner.