Oil change help

[daveburke114]

alrite guys, ive read the two oil stickys but its confused me even more, as im new to oil (my dad usually does it for me, but hes away at the moment!)

ive got mobil1 fully synthetic in there at the mo, but cant afford to keep running it on that at the moment (cash is a bit tight)

However in the garage i have litres and litres of 15w40 Shell Mineral Oil, which ideally id like to put in becuase the cars got an oil leak, and dont want the £40-for-4.5litres mobil one to kepp pissing out on the floor!

ive just got a new oil filter, so can someone tell me if
a) its ok to run my '89 325i sport on this oil
b) do i need to flush the system?

or is it just a case of draining the old oil, replacing the filter and filling her up with mineral?

(i can also get 5w40 Ford semi-synthetic, or Vauxhall fully synthetic for cheap, but dont really want the expense if its ok to run on mineral)

cheers for the help
dave

[georgen]

I think that the 15w40 may be a little thick for your M20, but I'm sure that somebody will confirm this soon. I'd personally use Castrol GTX / Magnatec 10W40, as this is all a M20 needs. I believe that Tesco's are selling a 4 ltr tub of GTX for £12 at the mo...

[e30den]

10w40 is the correct oil to use 15/40 will do no harm, as these old engines were,nt designed to run on fully synthetic there is nothing to gain by using mobil 1 imo

[daveburke114]

ok, oil change went ok, so im hoping no-one pipes up now with 'no, its gona wreck ur engine' lol

cheers
dave