When you use long oil change intervals for your car, please check your oil level at least once a month.

My son-in-law is a Subaru tech and a while ago they had to do oil use tests on many of their NEW engines. They filled the oil carefully and asked the owners to come back after 1000 miles to check for oil loss.

He is the top tech at his dealership and had to re-ring several new engines.

He won an award from Subaru for solving a problem with this process. If a tech followed Subaru's manual to install the timing chain, it was noisy. He found a place to put some vice-grips on the chain during its installation to eliminate the noise.

He also got an award for finding a sporadic electrical issue that killed the engine. There was a broken connection on the back if the main fuse block - the fix involved a whole new wiring system!

I switched over my new to me 1993 940 from dyno to 5-40 EU blend Mobil-1
last summer and have only put about 2000 miles. The oil was black and
I just changed it after 10 months.
I suppose the full synthetic is doing it's trick and cleaning out the engine.

According to Mobil-1 You get 10,000 miles or 1 year for the full synthetic.

This is a ball park number inflenced by the Mobil-1 sales department, so
if your oil looks OK maybe you can slide.

If you want to get technical, send your oil out for analysis and let them tell you.
My pal does that with his Volvo Penta deisel in his boat.

Another item in low mileage cars is the T-belt that will age over the years,
so worry about that more than the oil with an interference engine.

Cheers, Bill

I think you're doing just fine with a 5000mile/1 year oil change interval. Modern intervals are all in the range of 10-15k miles or 1 year even with "dino" oil. Don't sweat it.

I've never heard a straight answer on the argument for changing the oil once a year regardless of miles. Does something go sour, leach out of the aluminum/iron/steel/varnish?

Cheers,
Will
--
XC60 / Odyssey

I would say you are being over enthusiastic with your changes. Check your driver's handbook, I'd think that you can at least double the time/mileage between changes. With low miles and an average style of driving I'd not be unhappy stretching it out a lot further than that.