Which oil is best ?

[imperial21]

Hi
As its such nice weather i thought i would i service my car this weekend (if only ! )
I have the choice of 2 oils to use which is best I have 5w 30 fully synthetic or 10w 40 fully synthetic ??? I bought both cheap in advance, My car is a Xantia HDI 110bhp with 125k miles, I change every 6 months ish around 6500 miles a time, I have done the last 2 changes with the 5w 30.
Thanks

[Peter.N.]

I have always used the cheapest oil I can find with the correct spec and for the Hdi that's Morris's semi synthetic 15/40 which until recently was about £10.00 for five litres at Trago Mills. I have always used their cheap oil and have had two XMs that have reached nearly 300,000 miles.

You have it right with your oil change intervals, regular changes are far more important than expensive oil.

Peter

[addo]

The best oil is the one you personally believe in.

[imperial21]

Both oils are cheap in my mind the 10w 40 i bought for £20 off a friend who never used it, Its Shell Helix fully syth, the 5w 30 i bought for about £2.50 a ltr, and is an Elf fully synth. The handbook never really recomends any particular just a range !

[addo]

You should never mix brands of oil. They can curdle and produce an abrasive grit inside your motor!

Always use a clean funnel, too. You can't be over-careful these days...

[citronut]

all the 10w 40 i but/use is semi synthetic not fully synthetic,

were do you get 5w 30 fully synthetic for £2.50 a ltr, sounds very cheap to me cant remember off hand what i pay as i havnt bought any for a while, but its a lot more than your price and i pay trade price

regards malcolm

[HDI]

+1 for Morris oil, have used it for years. My Xantia is currently on 10W40 Semi synth.

[imperial21]

Just noticed its 5W 40 or 5W 30 oils, I did the service today and i used the 5W 40. If anyone is interested Euro car parts has an offer of 25% off service parts & brake parts. I bought Air, Oil, Fuel filters for the xantia & Air & Oil filter for my wifes Clio and all came to £21.58 !! I did nt buy the cheapest parts.