Not Trying to start another oil debate...

[dmk]

I'm heading out on a trip and need to change the oil. I've been running Mobil 1 15w-50, but saw a greatt deal on Castrol 20w-50. I have no idea what the difference is. Am I safe to use 20w-50 onn my '04 1150r? Thanks.

[Boxer]

Yes, and as our friend Towerworker will confirm, don't forget to replace the coolant in the 2 radiators.

[DMM]

Not sure where you are, but 20w-50 should be fine. It's recommended by the local (DC) BMW shops.

Also read from Castrol that blending (e.g., 15w-50 and 20w-50 - if evenly blended makes 17.5w-50) isn't a problem. Even brand to brand shouldn't be an issue, tho each company will recommend keeping within brand. The recommendation was to use good quality and to stick with synth. or non-synth., depending on your choice.

[Dr. Strangelove]

Yes, for sure.
I run one or the other based on what is avaiable at Advance Auto. Sometimes they have a real special going including the filter.

Both are fine and have the Castrol in her now.

OT 50W oil is becoming a little scarce it seems.

[Xdot]

OT 50W oil is becoming a little scarce it seems.

This is only going to get worse. Light weight oils produce less friction and are considered "energy conserving." Everything that doesn't fall under the Green's umbrella is eventually going to be taken from us...

[bimmerguy]

My 2cents worth.
I understand that multiweight oil has products in it that get thicker as oil gets hotter.
So, what my tech tells me to never mix diff weights of oil, unless you are stuck in the boonies.
So if you run 20w50 , add only 20w50.
Also, if the engine has been broken in and run most of it's life on dyno oil, keep running it, BECAUSE the varnish on seals remains there and helps keep seal from leaking. Synthetic oil is VERY thin and will seep past old hard seals.
I run 10k miles in my car with synthetic, but it is water cooled.
My bike will get oil changes every 3k because there is no water to keep the OIL cool.

[MIXR]

The biggest issue with mixing oils is not the oil itself. It's the chemical reactions between the additives within the oil package. That's why you can usually change the oil index within a particular brand and type of oil without too much of a problem. Changing brands or oil type is where you now have (or may have) very different additives. No problem to get you out of a fix as any oil is better than no oil, but the reactions may generate sludging, or prevent the additives from doing their job. Hence the usual need to do a change (with filter) anytime you do a major change in the type of oil.