MikeM

It's also about the oil formulations you're using in the engine. Why not have an oil analysis done to set a base line to schedule future oil changes? I didn't think I would have to say to do it just once. Not every time.

In the meantime, an arbitrary schedule is nothing more than just guessing.

Me? I change about every 5000 miles on these old engines and I'm just guessing because I've never claimed to be too smart. But, I can also tell you, I've never had any engine failures due to my somewhat lax change schedule.

Lot's of commercial businesses use oil analysis evaluations to set their oil change schedule and they make their living out of equipment that has to run reliably and long term to avoid downtime due to overhaul or other repair.

If I drove 1000 miles in two days would I change the oil? Nope!

If I drove 5000 miles in one week would I change oil? Nope?

If I drove 10,000 miles in two weeks would I change oil! Probably but if I made a habit of it, I get an oil analysis and see how the oil was holding up!. And quit guessing1

Easy Rhino

At the rate my current engine leaks, I don't think an oil change is needed at all, just swap the filter every several thousand miles.

But seriously, oil changes are so cheap and easy, it doesn't matter if economics is your goal.

But I like the idea of an annual oil analysis, then drain and refill when the analysis says it's shot.

54greg

0Tampa Tuning

My fun cars only get about 1500 miles a year on them. In those 1500 miles, there's some good spirited driving. I usually change the oil once a year. This gives me a little time under the car making sure its all good.

SWCDuke

You should check your warranty documents. I believe GM requires at least an annual oil change, regardless of mileage, to maintain the emission system warranty.

Duke

Robert61

claf

For me it's every two years or 5000 which ever comes sooner in both the C! and C5. In 65 years of driving i have never had an oil related failure (in a street driven car)..

Jstan2014

lurch59

This is the correct answer, oil analysis to establish baseline and then you have an idea where you are if conditions are similar from year to year. I will add that paper elements have a 6 month lifespan and the clock starts ticking once you start the car and circulate the oil. My routine is to change the filter at the beginning of the driving season and that's it, presuming you do not drive more than 6 months. Synthetic media filters can last up to one year. My source is a major oil companies technical department.

lurch59

Oil analysis companies tell us this isn't an accurate way to determine suitability of oil. Viscosity is probably the most important parameter, and color of oil doesn't reveal anything about viscosity.

449er

Annually would be fine even for a conservative person, If you are so inclined, Blackstone Laboratories will do an oil analysis for less than $30. bucks, check them out online

CorvetteMikeB

THIS IS RECOMMEND FOR NEW ENGINES. FOR NEW CARS OR NEW CRATE ENGINES.


"How long can you go between oil changes?"


"The quick-lube chains usually recommend it be done every three months or 3,000 miles, but many mechanics would tell you that such frequent changes are overkill.

Indeed, most car owner's manuals recommend changing out the oil less frequently, usually after 5,000 or 7,500 miles. "

Rdelvalle

My other car a 1997 Porsche 993 has 41K miles. I drive it maybe 200 miles per year. The last oil change was three years ago. Sometimes I get a guilty feeling about not changing the oil but then I say a few more months. I do not really know when I am going to change it.
I am registered on the Porsche forum Rennlist and through postings I made friends with a retired engineer who was one of the creators of Mobil1 synthetic. He told me that they had during testing two cars with Mobil 1 that went 100,000 miles without oil change. Analysis of the 100,000 mile oil showed not deterioration, It was still good. When they released Mobil1 they recommended the oil to be changed every 25,000 miles but dealers did not go for it. Instead they recommended every 12,000 miles for Mobil1.
I am using Amzoil 10W-40 Synthetic (High Zinc formula) in the Corvette, and Mobil 1 15W-50 in the Porsche.

Robert61

Yeah. Maybe but I couldn't care less about what an oil analysis company says about me changing oil. I 've only been building engines of all types for 44 years. Modern fuel injected engine 5000 miles older carbed engine with no overdrive 3000. My BMW suggested around 12,000 mile intervals. My e350 Benz 8000 I think. I'll stay with my plans. My truck has 230,000 on it the Beemer 220,000. Seems to be going ok so far.

dplotkin

I used to change oil every October, as my collection grew from 3 to 5 to 8 it became a hassle and I noticed on some cars I was draining what looked like fresh oil. So I go by appearance, smell and feel. If it is clean, smells good and feels good I leave it alone for up to 2 years and I'm heated & humidity stabilized.

Dan

kenba

5 years or 3000 MI witch ever comes first.

Rdelvalle

Sounds good to me, I have two more years in the Porsche and five years on the Corvette before oil change.

SDVette

This issue has been rattling around in my head over the past 2 days.
It's certainly true that "looking" at the oil can't determine if the viscosity has broken down...
But think about it: What would cause a breakdown in viscosity??

- Lots of miles (not a factor for this discussion)
- Contaminants like water, fuel, combustion byproducts (these ARE visible)
- Excessive heat (perhaps a risk - although modern oils, especially synthetic, can take a lot without breaking down)

I guess what I'm saying is looking at the oil may be a pretty good indicator for this specific case (very low annual miles).

lurch59

You've certainly identified some causes of changes in viscosity, but there are others. Cheap oil has cheap viscosity index improvers which fracture easily and change the viscosity. We also want adequate TBN numbers which protect against acidic oil during storage. I think it is worth it to take the random occasional sample to see how your oil is fairing under your particular conditions, and get an idea how long you can go between changes.

GTOguy

This is sound reasoning. In cars with tight engines, I go by mileage only. Time doesn't affect oil that is not contaminated. I've used cars with 5 year old oil with no issues for decades. At 3,000-4,000 miles (depending on how it is driven---in town or open road) I change it. It could be twice a year or once every 5-7 years. On a worn engine, storing it with contaminated oil can cause pitting of the bearings and deterioration of internal engine components. Guys who drive 500 miles a year and change their oil every 6 months are wasting time and resources for zero gain, IMO and experience.