Just out of curiosity, is it harmful to mix brands of 2-stroke motor oil?  I have a bad oil guage which makes it unable to tell me when the oil is getting low.  Instead of spending $300 bucks on a new system I just put oil in when I fill the gas tank, or as needed.   I have been using the Evenrude oil, but I want to try the Pennzoil Marine Motoroil, but don't want to just mix them.  I think if I use the same WD rating it should be fine, but I don't know.

In today's world the companies have done a lot to lessen warranty issues by coming up with forumlas that are specifically designed to run in their engines.  I personally would not change.

Run Penzoil full synthetic and don't worry about it.  I only run the manufactors recommended oil in DFI motors but in my carburated and hot rod motors I've been running Penzoil synthetic for years.

In today's world the companies have done a lot to lessen warranty issues by coming up with forumlas that are specifically designed to run in their engines. I personally would not change.

Warranty is no issues, my engine is 'yesterday's' 1993 Johnson.  I just want to ensure the most out of my engine.

I use Pennzoil synthetic in my 1967 Evinrude 80.

I use whatever is on sale. Goes for boat, weedeaters, chainsaws, and anything else that requires mix. Never a problem in anything I have ever owned.

Wow! I just got my first engine and ran into this problem when I started winterizing last night! I have a Johnson 40 VRO and what's left in tank is red. I, however, got some marine 2-stroke oil and it's blue. I had no idea until I opened the caps for both and then I panicked a little.

After researching on the Internet, texting a couple buddies and calling a parts shop, I decided it was OK to mix; but I know not everyone agrees with that. I came away with: if it's "TCW-3" it should be OK to mix. Maybe not the way to go with big new engines, but for smaller, older, outboards the consensus was that it's OK. I will stay with this same brand from here on out though.

According to what I have been told, each motor manufacturer suggests the oil to use.

I use Mercury oil for my Mercury motor even though I could purchase less expensive oil.

Just my two cents.