Change Oil on age or miles?

[PeteK]

Blackstone labs tested some old oil, both unused from bottles, and used sitting in edges for a long time, to settle this question:

Motor Oil Age Doesn’t Matter as Much as Mileage: Study

An oil testing laboratory has found that the conventional wisdom of six-month oil changes might be a waste of your money.

www.thedrive.com

 

[HighHP]

Pete - I know you already knew the answer.

Age is not a factor for oil alone. Now, if an engine sits for years and only gets started periodically and run in place, the water content in the oil will increase with every start and that is not good. Then the aged oil with increasing water content is baaaddddd.

 

[fjpikul]

I believe this is what Rich has always preached.

 

[PeteK]

Yes, starts and short runs, then shutdowns aren't good. The cure for that is to get out and DRIVE the damn thing!

 

[B.M.F.]

Best thing to do is start it up and let it run to operating temperatures periodically.. I think its crazy people think they need to change the oil in a sub 1000 mile car or the transfluid..

 

[PeteK]

And throwing away oil “before its time,” just puts more junk into the environment.

 

[twobjshelbys]

I think its crazy people think they need to change the oil in a sub 1000 mile car or the transfluid..

Oil deteriorates from contaminants. Most come from use. Water can condense but is evaporated if the engine is at operating temperature.

In the absence of contaminants oil is already somewhere between 252 and 65 million years old. It does not rot. Another couple of years sitting in a can or oil pan will not make it go bad.

 

[HighHP]

Oil deteriorates from contaminants. Most come from use. Water can condense but is evaporated if the engine is at operating temperature.

In the absence of contaminants oil is already somewhere between 252 and 65 million years old. It does not rot. Another couple of years sitting in a can or oil pan will not make it go bad.

LOL. Excellent point.

Some time at operating temp is required to evaporate the water absorbed during the start warm up cycle. Hot oil flinging off the crank will certainly evaporate the water over time.

 

[GT@50]

I change my oil once a year, about 2000 miles and 1-2 track days. If I tracked more, I'd change it more. If I didn't track it I'd still change it once a year. I do it at the end of the year so it doesn't sit several winter months with contaminated oil. A tad bit of coolant could rust components. A tad bit of fuel could corrode components. The contaminates may be insignificant or none at all, and no problem short term, but long term like 2 years/4k miles they may do actual damage. I may also catch something before it's a larger problem. Say I had slight coolant in the oil. Not enough to see but enough to measure scientifically. Not enough that would necessitate a repair be performed, it could be from porosity. If I change it at 2k, no biggie. Wait 10k, hopefully you're OK.
Get the original oil out of the trans too and clean the screen. The first time it will be the worst, all the sharp edges will have been deburred and on the screen/magnet. After that I'll do it every 10k.
I'll do the SC every 5 years.
I dilute the coolant every couple years, but all I do is suck out the reservoirs and replenish with new.
Brake and clutch fluid get flushed yearly. Clutch is probably more warranted but I do both. Suck out reservoir, add new and bleed out about a pint total.
P/S I dilute every couple years. Suck out reservoir, refill, run, suck out, refill, run, etc. until a quart has been used up.
Fuel gets swapped out after about 45 miles on a track day.
It's good to regularly inspect this stuff and dump the dirt off the pans. Every car I've worked on has had loose/missing fasteners in various places.
This is just how I feel. It gives me peace of mind and I get to be all touchy, feely with this beautiful machine.

 

[PeteK]

To add to twoshelbys' observation that oil base is already millions of years old (synthetics excepted), remember that motor oil is refined and designed to last inside an engine exposed to temperatures of several hundred degrees F, getting splashed, aerated, contaminated, and sheared for many hours and miles. It ain't gonna go bad just sitting in a cool sump/tank, let alone in a bottle on a shelf.

If anyone is concerned about contaminants in the oil, do oil sampling like I do. It's only 30 bucks at Blackstone and will tell you positively if your oil has water, antifreeze, or other contaminants, and the viscosity and TBN number (which indicates whether the oil is becoming acidic )

But, it's your money, so spend it however it makes you happy.

 

[twobjshelbys]

But, it's your money, so spend it however it makes you happy.

My gt, cobra and mustangs were weekend toys for drives in the local area a couple of times a month. Simply pulling the car into the driveway and running the engine til the temp gauge gets to normal isn't a substitute for a short drive that gets all the fluids circulated. even around the block is better than nothing. Often makes me wonder what true collectors like Leno and Pratte did. I know Leno drives some of his but he has way more than can be warmed up every month.

An oil test can make sense but I've found I can change the oil on our daily drivers at 5k miles for less than the test so I just do the change.

 

[PeteK]

Based on the past 60,000 miles of oil testing in my GT, I now do 10,000 mile oil changes. No increase in wear metals/mile so far, and TBN ends up around 3. Blackstone suggested I could go more than 15,000 miles.

I still use the Motorcraft 5W-50 stuff. I might also try a different oil and test it at 5,000 miles.

 

[HighHP]

Many turbine generator and hydro power plants never change the oil. They do frequent oil analysis and add treatment products as needed.

Pete - didn't you spend time on aircraft carriers? Do you know if they changed oil in the steam turbines?

 

[extrap]

How bout the air filter?

 

[PeteK]

Sure, we just put or carriers up on blocks in drydock so we can get to the oil drain plug down on the keel...

Ship steam turbines do not have regular change intervals and generally only change oil if contaminated. As you noted, the oil is finely filtered and regularly tested and adjusted. I'm pretty sure the same processes apply to the big marine low-speed diesels too.