Oil & Fuel Add 20 year old oil to motor?

CobyRupert · Jul 11, 2022

Made the trip to mom’s house to mow her lawn with her little Honda Harmony riding mower. Forgot to bring a quart of motor oil to top off the dipstick.

The oil level was “just” below the mark on the stick. That motor only takes ~1.5qt of oil, so there’s not much to loose (if a leak suddenly got worse), and I’m occasionally mowing on some hills.

There was a case of unopened Castro 10w-30 oil in her garage. My late dad bought it 20+ years ago. I shook a bottle up, opened it, and it looked like…oil.

To use or not? I added about about 1/2 to 3/4 cup.

Was it better than nothing? Or worse than (adding) nothing?

LS Tractor Owner · Jul 11, 2022

I don't think there would be any issues at all. I'm not a specialist chemical engineer, but if it was sealed.... it's good.

ROUSTABOUT · Jul 11, 2022

LS Tractor Owner said:
I don't think there would be any issues at all. I'm not a specialist chemical engineer, but if it was sealed.... it's good.

I never worried about old stuff until I got old. Then I realized I was too old to worry about it.

ruffdog · Jul 11, 2022

Agree with the above posts....use it.

ruffdog · Jul 11, 2022

The only problem would be if a person uses old oil in a modern auto. Some of the heavy metals may raise havoc with the emissions.

gstrom99 · Jul 11, 2022

Yes. Use it w/o worry.

Captain Dirty · Jul 11, 2022

For further reassurance: On the Castrol bottle will be a printed, "API donut". The center contains the viscosity, and the top part of the donut shows the API service rating "API Service S_" where the blank is likely to be an "H" (the latest and highest rating from 1993 to 1996), a "J" ('96 to 2001), or an "L" ('01 to '04). (Current ratings are SN, SP.) The ratings are said to be backward compatible.
The Honda Harmony was a machine of the '90s. If your late father kept the owner's manual, it would likely specify the rating SH or SJ. Even if you cannot find the manual, do not lose sleep over using 20 YO oil in a 30 YO motor.

Have tractor did travel · Jul 11, 2022

Using old oil was better than nothing. However, I take a divergent view than the others.
Oil additives begin to lose their effectiveness in five years. OK to use in a low value motor, especially mixed with a greater quantity of new oil. But do not use by itself, and I'd not use it in an expensive motor. Good that you shook the container - any additives that separated, were remixed, and fully poured from the container.