Which engine oil & What tyres for 17inch alloys pls?

[BONGODADDY]

I know these two questions have been asked many times, but after looking through the answers previously looks like there are a few different responses, probably there is more than one answer?

Anyway, just need to know what engine oil is the "Best" for a 2.5 d, and i am considering upgrading my 15inch alloys later in the year to 17inch but do not want to make the van unstable in anyway (the tyres i have at the moment are 100 h rated and 215 65 15 which i understand are correct and standard), If i do upgarde to 17inch wheels and tyres i would prefer to fit a set that i dont have to try to work out my actual speed compared to what the speedo is reading due to any variance from my 15 inch wheels (Is there a tyre size for 17 inch that eliminates both of the issues?).

Thanks to anyone who can help.

[dave_aber]

All you ever wanted to know about tyres etc.

Fairly comprehensive, but should answer all your wheel/tyre size questions.

[francophile1947]

Oil should be 5W/30, but I use Shell Helix 10W/40 because that's what most of the dealers use.
215/55x17 is just about the nearest circumference to the 215/65x15 standard tyres. I've got 225/55x17 fitted and the speedo is virtually spot on with the sat nav. You can do your own comparisons here http://www.miata.net/garage/tirecalc.html

[BONGODADDY]

Thanks for your replies, got my oil and topped up the level, i followed your advice John and purchased 10w/40 castrol gtx diesel as that was the "Best Branded" oil that they had.

Thanks again.
Will let you know if/when i upgrade my wheels.