How often to change motor oil fact /or fiction

[Anthony C.]

Ok .. woke up early this morning and pondering this question .. how often does everyone change there motor oil ? To be honest I drive about 5-700 miles a year and change every fall .. however I am starting to question myself if I am wasting my money . Every year when I drop the oil it looks brand new . 🤔🤔🤔

[Duke W.]

Re: How often to change motor oil fact /or fiction

There's no hard and fast answer to your question, but given your low annual mileage, and assuming you don't drive "short trips", like less than 15-20 minutes of engine operation in mild to warm temperatures, you'll probably be fine going two and maybe even three years assuming the car has a properly functioning PCV system.

Of course, you should be using C-category oil in the 15W-40 grade, assuming you don't do consistent cold starts below about 20 degrees F.

Heat over time causes engine oil to oxidize and that's the primary reason it darkens with age/miles, but excess blowby or an ineffective crankcase ventilation system (which includes the pre PCV "road draft tubes") can also cause the oil to color.

Today's engine oils are much more resistant to oxidation than oils of decades ago, which is why longer change intervals are okay in modern cars, but I believe GM still requires a minimum annual engine oil change, regardless of mileage, for modern Corvettes to maintain warranty coverage, but if you do a lot of highway driving in mild weather the oil change monitor may let you go up to 15,000 miles in no more than a year before a change is recommended.

If you store the car during the winter months and an oil change is near due, do it prior to storage. The clock doesn't run on fresh oil in the crankcase while the car is stored.

Don't forget that engine coolant and brake fluid should be changed periodically, and Positraction axles should get an oil change at least every 30K miles to get rid of the clutch wear particles.

Duke

[Mark E.]

Re: How often to change motor oil fact /or fiction

I like to inspect the chassis annually, checking for leaks and loose things. While under there, it's not much more work to change the oil and filter, regardless of mileage. Even using synthetic, a LOF cost less than $40.

Duke is right about changing other fluids. It's not uncommon to see owners change oil regularly, yet neglect coolant, brake, trans, clutch, differential fluids.

[Keith M.]

Re: How often to change motor oil fact /or fiction

Total personal thing. Car will be fine. I would shoot for once a year. Money wasting should not even be a thought. I mean..u own a vette! $50 once a year maint on a vehicle worth how much?

[Owen L.]

Re: How often to change motor oil fact /or fiction

My engine builder recommended every 1-2 years given the limited mileage my cars see. The worst thing for our types of usage was alluded to in Duke's reply about short trips or not fully heating the engine. Ensuring the engine comes to full heat evaporates condensation.

Here is part of the abstract from a short paper on it from a test equipment maker:

Moisture contamination in in-service lube oils is perhaps one of the most destructive forms of engine corrosion second only to particle contamination. Water contamination in oil can be categorized into three forms of water; Free, emulsified, and dissolved. All forms of water have direct consequences to the oil and gears of the engine, but indirect consequences as well. Direct consequences include changes in pH and viscosity which can be problematic in themselves. Other factors that affect engine corrosion are contamination of glycol, soot, and particle corrosion. The presence of water exacerbates each of these factors and can cause irreparable damage to the engine.

[Leif A.]

Re: How often to change motor oil fact /or fiction

I drive mine around 6000 miles per year, so she get's an oil change bi-annually...every 3000 miles.

[Anthony C.]

Re: How often to change motor oil fact /or fiction

There's no hard and fast answer to your question, but given your low annual mileage, and assuming you don't drive "short trips", like less than 15-20 minutes of engine operation in mild to warm temperatures, you'll probably be fine going two and maybe even three years assuming the car has a properly functioning PCV system.

Of course, you should be using C-category oil in the 15W-40 grade, assuming you don't do consistent cold starts below about 20 degrees F.

Heat over time causes engine oil to oxidize and that's the primary reason it darkens with age/miles, but excess blowby or an ineffective crankcase ventilation system (which includes the pre PCV "road draft tubes") can also cause the oil to color.

Today's engine oils are much more resistant to oxidation than oils of decades ago, which is why longer change intervals are okay in modern cars, but I believe GM still requires a minimum annual engine oil change, regardless of mileage, for modern Corvettes to maintain warranty coverage, but if you do a lot of highway driving in mild weather the oil change monitor may let you go up to 15,000 miles in no more than a year before a change is recommended.

If you store the car during the winter months and an oil change is near due, do it prior to storage. The clock doesn't run on fresh oil in the crankcase while the car is stored.

Don't forget that engine coolant and brake fluid should be changed periodically, and Positraction axles should get an oil change at least every 30K miles to get rid of the clutch wear particles.

Duke

g thanks duke appreciate your input

[Anthony C.]

Re: How often to change motor oil fact /or fiction

Thanks mark 👍

[Anthony C.]

Re: How often to change motor oil fact /or fiction

Thanks leif 👍