10w-30 is what is in the manual forthe XR8, but I just had a 10,000 k service on my BA XR8 this week, and the dealer said that that 0-40 Castrol R is now the "in oil". It is used in GT and GTp. I am a little warry but I called Castrol and they also said it is perfect for the XR8 260 Kw beast, so in it went?.. $92.00 so it got to be good?????
I find it interesting when Ford cant or wont tell you, but walk into a dealer ship and they say we have a range of oils available to use. I have been a mobil synthetic user for years and swear by it. I used 10-30 Mobil 1 from 3000K in this BA XR8, so Castrol is a "new venture" for me. If it stuffs up I will be down their throat so quick. yes Yankee land has some strange oil grades. EPA is certainly an issue in the US. I was surprised that the manual said 10-30 to be honest. I was getting an early tick when cold, but have nto had it since the change on Tuesday. It is early days.. cheers to all
I can't find a 10w-40 on the Mobil website, do you mean 0w-40?
It seems that both the Mobil1 0w-40 and Castrol R 0w-40 are much the same, both are ACEA A3 rated (good as it gets). The Castrol has a TBN of 10 so it should be good for extended mileage. The Mobil didn't have a TBN in the specs on the website, I'll send em an email.
The Mobil runs a bit thicker at high temps, but there is not much difference. Sulphated ash for Mobil was 1.2, not shown on the Castrol website.
I am buggered if I know how anybody can compare oils, when each company publishes different criteria, and chooses to leave out others.