What Types Of Oil Properties Matter For An EREV Whose Engine Is barely Run?

Joined
May 21, 2025
Messages
10
I own a 2021 BMW i3S REX, meaning it's an electric car with a small gasoline generator that cuts on once my battery has depleted to give me an extra 80 miles of range before I have to fill back up.

These range extenders are often a cause of concern because of just how infrequently they're used, especially given that my i3 goes 150 miles on electric — far more than I need.

So my little two-cylinder engine rarely fires up, and when it does, it's just for like 5 miles or so, shutting off at lights and while coasting.

It's an interesting use case for an engine, involving lots of cold oil, short trips, and start/stops.

Are there any 0W30 oils that might be better than others for this range extender, whose oil I change every 2 years?
 
The owner's manual says nothing.

But I'm told a sticker on the engine says 0W-30.

There is not enough room on the oil cap so they just put the viscosity grade.

However, in the owner's manual they should have more info especially being a BMW. Those guys are very finicky about their oil. :ROFLMAO:

Yon can always download the pdf if you don't have the owner's manual. And easier to search the pdf.
 
It’s a bit similar case to my Prius Prime - it’s been over 2 months since I filled up with gasoline and I still have over 3/4 of a tank.

I just check the dipstick and the underside of the oil fill cap for signs of moisture -whitish mayonnaise. If I see that, I force the engine to run by running the battery low or going into charge mode for about 30 minutes to get the engine hot and evaporate the moisture.

I don’t think that the oil grade or brand is all that critical but keeping it dry by an occasional longer run is important to me - even if it costs burning a tiny bit more fuel.
 
Back
Top Bottom