Which Oil To Use

[afundora]

I’m getting ready to change the oil on my 1998 740I that I bought this month, my question is; the car has non-synthetic oil now, should I switch to synthetic oil, if so which brand/Type. The car has 38000 original miles.

Thanks…Al

[bigsix]

You can switch to synthetic at any time . the only drawback is that synthetics will sometime leak. i usually recomend either Mobil 1 or Castrol Syntec . The oil grades i use on my bigsix is Castrol Syntec
5W-50 , this way i can run the same oil year round.

[olesenp]

Well, before I start , be aware that most car people have strong opinions on which brand of oil to use. No matter what brand you use, I think the evidence is strong that synthetic oil is worth the switch. It is clearly superior on all fronts over petroleum based oils.

I am partial to Amsoil (www.amsoil.com). It is not available in stores and can be purchased directly from the company or from a distributor. Before you switch to synthetic it is probably wise to run an engine cleaner through the engine to remove some of the deposits left from petroleum oil. This process only needs to be done once, assuming you stick with synthetic.

There is a word of caution. If you have a higher mileage engine, you may uncover oil "leaks" that weren't there before. The reason is that once you run the engine cleaner through, the petroleum deposits that had accumulated are removed. Some of these deposits may have been plugging seal leaks. Compounding the problem is that synthetic is a better lubricant and will find any openings that are there. Just make sure you check your oil level frequently after the switch. I have converted several vehicles with over 90K miles and haven't had any major problems with this. If you do discover a leak, the solution is to have the offending gasket replaced.

I hope that helps. Good luck.

[Bear]

I agree that synthetics are great. I have also heard some engines after switchover from Din Oil to synthetic may leak. I have not personally found this to be true and I have the synthetic in three automobiles. I use Mobil 1 15W50, chnage oil once a year or every 15,000 miles, whichever comes first, and I change the oil filter every 5,000 miles.