Am I wasting oil by changing early ?

[Schurkey]

Feedback fuel injection and overdrive transmissions are responsible for extended oil change intervals. I used to go ~13,000 miles on the Trailblazer I-6, but now I'm going double that, with a filter change at 13K, and topping-off as needed. (Heavily highway use, but some in-town, too.) I have zero expectation you could duplicate that with a carburetor and a non-overdrive transmission.

The ONLY way to know is to send off oil samples so the oil can be analyzed.

About the only times the oil sample reports have detected a problem, the thermostat was faulty. Had that happen on the Trailblazer, and on a '92 Lumina.

[BILL-C]

Feedback fuel injection and overdrive transmissions are responsible for extended oil change intervals. I used to go ~13,000 miles on the Trailblazer I-6, but now I'm going double that, with a filter change at 13K, and topping-off as needed. (Heavily highway use, but some in-town, too.) I have zero expectation you could duplicate that with a carburetor and a non-overdrive transmission.

The ONLY way to know is to send off oil samples so the oil can be analyzed.

About the only times the oil sample reports have detected a problem, the thermostat was faulty. Had that happen on the Trailblazer, and on a '92 Lumina.

How many miles a year do you drive? I only drive about 13k in a full year. If i only changed my oil once every 2 years it would look like roofing tar.

[Schurkey]

Feedback fuel injection and overdrive transmissions are responsible for extended oil change intervals. I used to go ~13,000 miles on the Trailblazer I-6, but now I'm going double that, with a filter change at 13K, and topping-off as needed. (Heavily highway use, but some in-town, too.) I have zero expectation you could duplicate that with a carburetor and a non-overdrive transmission.

The ONLY way to know is to send off oil samples so the oil can be analyzed.

About the only times the oil sample reports have detected a problem, the thermostat was faulty. Had that happen on the Trailblazer, and on a '92 Lumina.

How many miles a year do you drive? I only drive about 13k in a full year. If i only changed my oil once every 2 years it would look like roofing tar.

I'm going about 1 1/2 years between changes. It isn't two years, but more than one, with the Trailblazer.

Some of the other vehicles, I have to write the date 'n' mileage on the filter or I'd lose track. Two, three years...maybe more.

[BILL-C]

One time i pulled the valve cover off of a chevy 4 cyl s-10 to fix an oil leak. There was so much sludge inside you could barely see rockers. What a mess! The latest oil change sticker on windsheild indicated oil was changed 12 k miles ago. The addative package in oil is used up before the oil is "worn out". Once the anti oxidents and detergents are overwhelmed, then it gets ugly inside very quickly. 36 years of experience rebuilding engines has shown me that an engine lasts longer if it's kept clean inside.

[BOOT]

I got a 4.3 out back you can stick a screw driver in the sludge n it'll stand, my buddy didn't believe in changing the oil because of a steady leak and he kept topping it off with cheap no-name gas station oil. Looks like someone dumped a bucket of old grease inside it. Reman engine that made it 50k b4 a rod let go(20k b4 he got it).


I bought some of that Amsoil engine flush to try on a not too bad 90k sbc that was maintained ok but too many short trips I think.

[Newold1]

When you really think it through you will usually come to the realization that how oils live in an engine will pretty much be determined by the quality of the oil you are using, the type of engine you are using it in, the effectiveness of the filtration system, the age of the engine and the way that engine is being used and loaded in the vehicle. All of these factors will require different weights and blends of oil, different oil change intervals and filter types and change intervals. Got an older engine that is burning some oil and putting a moderate amount of carbonized oil fuel residues in the oil, that oil will have to have some decent detergent characteristics and be changed much more often than an engine that is running clean like a lot of these new low emissions clean running OEM new car and truck engines. Run your engines in dirty dusty environments, have the engine running in temperature extremes, especially high heats, that oil is going to have to be changed sooner than engines that run in cleaner environments and milder stable ambient temperatures. Have engines that tend to run fat and rich and tend to run lower air/fuel ratios and have moderate to extreme rpm ranges, that oil will need special servicing.
What I am trying to say here I guess is that there is obviously no one hard fast rule on how often you are going to have to change your oil, service the filter or what particular oil type you are needing to run. It all depends on how and where the oil is being used. best bet is to take the experiences and advise of others who have had good results when using oil and change intervals in a similar engine and similar use.
Are you anymore confused now then when you started reading these posts?? YEP! I know I am!

[Schurkey]

The "hard and fast rule" is that you cannot know unless you do oil sampling for analysis.

Given feedback fuel injection, overdrive transmissions, and an engine that starts out in good mechanical condition, oil change intervals can be shockingly long.

[Bradley67]

I'm always surprised when people spend a lot of money building a high performance engine and then put "cheap" oil in it. What is the cost to do two oil changes a year compared to not.
On high performance street engines that only see 1000 to 2000 miles a season I put the best oil (POA #3) SYN with the correct weight based on engine tolerances and driving conditions. Then it gets changed every 500 miles. Total cost about $150 annually.
When you look at the rollers and cam after 10k miles they look as if they were just taken out of the box.
IMHO the cost of the oil change is no comparison to worn out engine parts.
On my daily drivers the oil- filter gets changed every 5,000.

[rally]

I change oil every 4,000 miles. Oil is cheap enough with filter and i like to take care of the engine.

[MadBill]

Not recommend, but many years ago I accidentally went 37,000 km (~23,000 miles), mostly highway, on single sump of oil in my then-150,000 km. carbureted 3-banger Pontiac Firefly (aka Geo Metro). Guilt-ridden, I sent out a sample for testing. Report came back "suitable for further service."
It was still using less than a liter per 5,000 km when I scrapped it at ~ 225,000 miles.

[Schurkey]

I change oil every 4,000 miles. Oil is cheap enough with filter and i like to take care of the engine.

Are you "taking care of the engine" or are you taking care of your insecurities?

Until you send off samples for analysis, you won't know.

Some engines/applications will NEED the oil changed at 4K or even sooner. Others are "just getting started" at 4K and have another 20K+ service life left.

[Roundybout]

My daily has an oil change reminder thingy. I can go 3 times the distance in summer months compared to winter according to it. I average about 4000 miles in winter and currently have about 8500 miles on this change and I can go another 25%.

How do those things calculate that? Time spent cold, cold starts, short trips, average RPM's and so on? It can't factor synthetic vs Dino oil can it? It appears cold starts are what murders oil life and the number of cold starts. I suspect if I lived in FL I could go 15,000 miles on a change. I use Mobil 1 0w/30w by the way.

[rally]

I change oil every 4,000 miles. Oil is cheap enough with filter and i like to take care of the engine.

Are you "taking care of the engine" or are you taking care of your insecurities?

Until you send off samples for analysis, you won't know.

Some engines/applications will NEED the oil changed at 4K or even sooner. Others are "just getting started" at 4K and have another 20K+ service life left.

True, depends on your application, short drives, long highway driving. Get that. I know motor oils are so much better now, and engines, rings, are made of better quality parts. But like you stated, to each his own.

[Schurkey]

My daily has an oil change reminder thingy. I can go 3 times the distance in summer months compared to winter according to it. I average about 4000 miles in winter and currently have about 8500 miles on this change and I can go another 25%.

How do those things calculate that? Time spent cold, cold starts, short trips, average RPM's and so on? It can't factor synthetic vs Dino oil can it? It appears cold starts are what murders oil life and the number of cold starts. I suspect if I lived in FL I could go 15,000 miles on a change. I use Mobil 1 0w/30w by the way.

They calculate oil life the way they were designed to.

I heard that the early Ford oil-life monitors were a mileage counter. Beyond primitive.

Others have a pretty-good protocol for "guessing" the oil life. Yeah, it includes engine temperature, throttle position, time, miles, RPM, probably trans gear, and whatever else the engineers can think of. NONE of them have an actual sensor that determines the quality of the oil.

[j-c-c]

Roundybot: "I suspect if I lived in FL I could go 15,000 miles on a change" Mmmmm....... I'm Florida I might try that.

On our diesel Cat generators, actual fuel consumed seems to be the most important factor, combined with oil testing history.