Oil change intervals

[tradosaurus]

Oil threads seem to bring out the opinions from everyone, not sure how many of us are oil experts! I'm sure there are many factors in determining when to change your engine oil. But I think certain engines need a bit more care in that department. These newer boosted engines seem to be happier with more frequent changes as an example. Does size matter? The age old question....

This was interesting:

https://www.reddit.com/r/Justrolledintotheshop/comments/xfcflt

That picture almost looks like a transfer case.

 

[Williy]

JimRB
If you engine is using oil and your using 0W or
5W switch to 10W or 15W see if that will help
or get the top number higher it works!
I know that guys when they vehicles started
using oil they switched from 10W30 to straight
30W or 40W and cut the oil consumption down

willy

 

[mo1]

a question for the oil experts that i haven't seen addressed: on a smaller truck engine (4.5 qts w/filter), do the same recommended oil changes intervals w/synthetic apply the same as the bigger sump capacities of today's truck engines? so simply by virtue of sump capacity, will a 4.5 qt capacity accumulate contaminates faster than say a v8?

also, agree changing according to severe vs normal service. to me, strictly town use, cold starts, mall cruising is more severe than longer runs, & should be changed more often. strictly my opinion.

as a footnote, my 4cyl Toyota 4x4 (prior to Tacoma) purchased new in '92 (only new i've owned) single owner, currently has 298K on original engine/drive train, never been broken into, uses qt or less every 5k change. i would never dream of going 10k on a change. i go 5k
is this flawed thinking on my part to change more often on a smaller engine. thx in advance. i'm looking forward to joining the 300k club 30 yrs in the making, regards

The manufacturer will specify a certain oil change interval for the engine as set up with stock components, this takes into account the total amount of oil in the system. Putting a higher-capacity pan in a specific engine will result in the larger quantity of oil taking longer to accumulate the same concentration of contaminants, theoretically extending the oil change interval. There are more specifics but if you do add a larger pan to hold more oil, I would use an oil analysis to guide your oil change intervals.

Certainly there are engines with larger quantities of oil than in the past, and that likely does extend the oil change interval. My truck's small block V8 takes almost 8 quarts of oil, back in the day a small-block would take about six. I would expect the size of the oil pan and the oil change interval is probably guided by oil analysis on the test engines to ensure enough oil is in the system to withstand whatever oil change interval they want OR they set the oil change interval based on the setup they have chosen to use.

I find it amazing that so many people don't trust the manufacturers advice about oil change frequency, what grade gas to use, proper air pressure in tires, etc. With virtually no expertise, they somehow think they know more than the experts. My experience is just the opposite. If anything, the manufacturers recommendations are usually on the conservative side. They certainly don't want their reliability reputation tarnished by offering bad recommendations.

But people will still change their oil way too frequently because of good, but misguided intentions and bad assumptions.

There is discussion about this as we do know for a fact that there is at a minimum at least one non-engine-durability reason manufacturers use for specifying oil used in their engines. That would be the viscosity recommendations, and at least some of that is based on hitting federal government fuel mileage regulations. For example, we know that Ford has stated they specify only 5W-20 in most of their current gasoline engines in part due to EPA regs. Now what we don't know is if they knew they had to use 5W-20 for mileage reasons and designed the engine specifically around that viscosity of oil, or if the engines could actually use other grades of oil such as 5W-30 with better wear resistance but no ill effects. They have not done how some heavy duty on-road diesel engine makers have done and give recommendations for both the lower-viscosity (e.g. 10W-30) and higher-viscosity (e.g. 15W-40) oils to give us a clue about the engine's design.

Tire pressure can be a topic of discussion for a number of reasons. Even the manufacturers often note in their documentation that you may wish to adjust the pressure up to the maximum sidewall pressure based on operating conditions. They generally don't recommend lowering pressure but this can be done safely in certain situations if you have a load and speed table for the tire and stay within those parameters. Throw in the fact that there are a lot of tires that aren't the same tire or even the same size the OEM originally fit and you have a legitimate case to discuss running tires at pressures other than what's on the door jamb sticker.

Manufacturers will have a minimum octane recommendation but depending on the engine, response to higher octane fuel varies wildly. They may even note this themselves, generally with newer vehicles, and particularly with turbocharged DI vehicles.

 

[big bubba]

excellent write up. so the 30 yr old manual calls for 10/30 @ 3k intervals. so i'm going with 5k changes with 5/40 full syn (Castrol edge). at the smaller sump capacity, i feel comfortable with that.
oil analysis, yes, would be the more accurate judge. but @ $35 a change w/filter. i have no problems w/current pattern. consumption is around 1qt per change, no lie... 1.7k to go till the 300k club, looking forward.
thanks for the detailed note, regards

 

[Oaktree]

A wise person that believes in science instead of wives tales, hearsay, sales pitches, and glossy brochures, will change oil by analysis.

How does one get oil analyzed? I doubt it's something most of us can have done locally. Sounds like a major PITA to take a sample, mail it away to some outfit that does oil analysis and wait to see if it needs it. If not, wait ??? miles and repeat?

I know GM vehicles (maybe others?) have an indicator that shows how much oil life is left. How accurate are these?

 

[Yander]

A wise person that believes in science instead of wives tales, hearsay, sales pitches, and glossy brochures, will change oil by analysis.

I believe in owners manuals and common knowledge. You want to trust your engine to a lab analysis, certainly your right to do so. To think it makes you more wise than a man who reads and follows an owners manual, well I won't even say what that sounds like.

I personally like changing oil in my mowers and tractors. Mowers and tractors every year or 70ish hours, which ever comes first.

 

[nyone]

A good synthetic oil will not cause issues going by the oil change monitor.

The owners prior where "dealership" people so idk. Did on my car.

 

[JJT]

How does one get oil analyzed? I doubt it's something most of us can have done locally. Sounds like a major PITA to take a sample, mail it away to some outfit that does oil analysis and wait to see if it needs it. If not, wait ??? miles and repeat?

I know GM vehicles (maybe others?) have an indicator that shows how much oil life is left. How accurate are these?

Fairly easy, many truckers do this as a normal course of business. The oil analysis company sells you a kit, it's just a small plastic bottle. You fill it up, mail it out and get the results within a week. ~$25, money well spent for piece of mind. Like I said earlier, I was a 3kmi oil change guy for many, many years, I did the oil analysis deal a few time and now I'm doing 10kmi changes with plenty of oil life left. 10k is a nice easy number to remember. My tractors get an annual change, with ~60 hours a year worth of use.

Lots of truckers are doing 25Kmi+ oil changes. When an oil change is 10+ gallons, a $25 oil analysis is peanuts.

 

[newbury]

People will tell you that they tested their old oil and the lubrication properties are still excellent. That may be so, but you still have dirt grinding away within that 'still good' oil.

Then they didn't get their oil tested properly. A decent test woul show the "dirt".

How does one get oil analyzed? I doubt it's something most of us can have done locally. Sounds like a major PITA to take a sample, mail it away to some outfit that does oil analysis and wait to see if it needs it. If not, wait ??? miles and repeat?

I know GM vehicles (maybe others?) have an indicator that shows how much oil life is left. How accurate are these?

When you change your oil, grab a sample, note how many miles it had been used. Then you can see if it really needed changing.
I've a 2002 Ford F350 diesel, takes about 4 gallons of oil (w/ HPOP). When I first got it (2012) I changed the oil, then changed it (& filter) again after 5,000 miles and sent in a sample to Blackstone. They said it looked great. Next time I changed at ~ 10K, still looked great. Then sampled at 15K and 19K. Looked like w/ my driving habits (mostly long trips on interstate) I could go 20K easily on Rotella T6 with no worries.

Testing can get relatively expensive if you've got small oil capacity.

 

[buckeyefarmer]

My 2018 forester is starting to use some oil now, 141000 miles. Just had to replace a wheel bearing and the AC is starting to act up.

I change under 10k with Mobil 1.