lurch59

I never change oil until the analysis says so, which is rarely. I've got 3 vehicles with an average of 200,000 to 300,000 miles and I go 30k-50k miles and sometimes more between changes. However, I do run bypass filtration. Look at what the oil tribologists are doing, they are the experts, IMO you are changing the oil way too often because you are resisting the science, I am sure you are a very nice guy and are doing what works for you, I'm adding my experience and knowledge to the discussion.

ghostrider20

GTR1999

I put the car away when there is salt on the road- Mid Dec to March. I take it out and change the oil/filter. I don't care if I have 50 or 5000 miles on it. Cheap insurance. I never put more then 3000 miles a year on it so it gets the annual oil change. Now tune up goes to 8-10k miles so that is probably due this summer.

Auto trans - 30k- pan fit with drain plug
Diff - 8-10k real easy with a drain plug installed

DansYellow66

I bought one of these little, inexpensive kits a few years ago.



It works up to a point. I remember reading somewhere that fresh oils with high ZDDP content can check out from the start as partly used up. Something to play around with. For those who love to read reviews - suspicious, uneducated and otherwise -


But I'll admit mine has been in a drawer untouched for a couple of years. My cars are not abused or run hard. I drive easy until the oil temp is up if I have a gage or until the cold-high oil pressure has come down to normal for awhile. I change the oil when it looks like it's a good idea too and a couple of years or even three doesn't bother me much on a car run 3-500 miles a year.

Robert61

Frankie the Fink

Well, in the case of my classic cars, I try to change the oil annually, sometimes twice a year on cars I drive more than others. Partly for piece of mind, partly so I don't go so long between oil change intervals that I forget how to work with the funky oil filter canister.

I'm old...

As far as judging the need for an oil change by how "dirty" it looks - that's a non-starter for me; there are a bunch of reasons oil will darken some of which have to do with the modern additives used...

lurch59

Your life has been improved by reading this scintillating discussion! Changing your oil could not have done that for you.....

MikeM

It's tough to judge a book by it's cover. I know a guy that used to fool a lot with old greasy cars as a hobby. Later, he studied hard and obtained a degree in electrical engineering. Stayed with that a few years and went back to school. He now practices in gynecology and obstetrics. Sounds like a man for all seasons?

lurch59

Well, this is why folks should listen to me. While you were learning to work on engines, I spent 4 years of my life with my nose in chemistry books. Because I have interests in things with engines and do my own maintainance, I subscribed for years to an oil tribologists newsletter because I had the interest and the background to (mostly) understand what the engineers were talking about. The goal of oil triboligist engineers is to get the most longevity out of moving parts with the least amount of expense on maintainance. This is the goal of most here on the forum.

While you refer to your engine building experience as reason to change your oil too frequently, I refer to the studies I have read by lubrication experts. My dad was a tool and die machinist and made parts for NASA. He was very smart but when he had lubrication questions he asked me. Aircraft manufacturers recommend intervals because the oil typically falls out of spec after a certain number of hours, and there are no full synthetics for the GA fleet as far as I know. ( I own an airplane) There is no motivation for engine manufacturers to do the testing for extended drain intervals. Lycoming also says you can't run mogas but pilots have been doing it for decades saving millions of dollars in fuel costs.

My Mercedes mechanic installed a bypass filter on my 85 300 SD. When he found out I was going extended drain intervals with bypass filtration and analysis, he said "do you think you know more than the Mercedes engineers who recommend oil changes at 5k?" I told him technology had moved along since 1985. When he took the head off to do a valve job years later, he told me he was a believer, that my engine was about the cleanest engine he had worked on in his 40 years of experience.

Dirty looking oil typically refers to soot or carbon in the oil. My diesel engines have dirty oil the same day I change it. On the other hand, I have 2 propane powered vehicles which are almost soot free, so it looks clean when it is very old. Looking at the oil has no value for me. I test, and don't rely on luck, which is the secret of my sucess. Oil needs to be changed because it falls out of spec in some way, and if it is tested and in spec it is by definition still "suitable for continued use".

You sound like a very interesting fellow, we have a gentlemans disagreement, I hope our discussion helps others reading the thread.

Rdelvalle

I guess my comment on Mobile1 on my reply above got lost on my writing. Here it goes again for whatever is worth.
One of the Mobil development engineers that developed Mobil1, told me that they had tested Mobil1 in two cars that they drove for 100,000 miles without oil change. The oil went through extensive analysis testing after the 100,000 miles and it showed not deterioration. Based on their extensive testing while developing Mobil1 they recommended oil changes every 25,000 miles when they released the product.

Dealers pushed back because that cut into their profits and consequently agreed on 12,000 miles intervals. Dealers make money every time they change their oil so doubling the time interval halves their earnings.
I met the engineer in another forum and we became forum friends.

SDVette

lurch,

Your arguments are well stated.
However, I can't see how you link your machine shop finding "the cleanest" motor ever seen with extended oil use?
At BEST, it should be "no worse" than someone who changes every 3K miles.

Something else is a factor.

calwldlife

didn't original mobile1 have graphite?
and the new mobile1 is just synthetic?

lurch59

First let's state we are talking about diesels. I had the mechanic install a bypass filter which removes soot down to 2 microns. The average full flow filter doesn't trap particles until they reach 20 microns so my oil consistently has very small particles, in low amounts because when they agglomerate they are trapped by the filter earlier. Larger soot particles booger everything up. One more fact, TRW did a study years ago and determined that 60 percent of bearing wear was caused by particles in the 5-15 micron range. Now you begin to see the value of bypass filtration.

In your example where someone changes their oil every 3k miles, my engine will be cleaner because of the bypass, those without bypass will always have more soot particles in the harmful 5-20 micron range than someone with good bypass filtration. It's how I'm going about the extended drain intervals, not because of them, that my engine is cleaner. Sorry if I was unclear on this.

The kind of oil make a difference. Mineral based oils have paraffins and other undesireable molecules which react to form sludge etc. Cheap viscosity index improvers are prone to fracture. Remember, the shape and length of oil molecules determine the physical properties. Some molecules in cheap oils do very little for lubrication, and cause fluctuations in viscosity.

Do you need a bypass filter on your Corvette? I don't have one because there is not much soot produced in a gasoline engine. Folks are right, it's cheaper just to change the oil if the soot comes back elevated. I've got about 10 grand in my engine and I test it once a year or so, and last analysis came back with silicone a little high. The analysis thought it might be dirt getting in through an intake gasket or something. Sure enough the PCV had broken and was drawing in unfiltered air. My hot rod shop had already found it, but it's nice to see that it showed up at the oil analysis.

The gentleman who looks at his oil for cleanliness is doing a crude soot analysis. Labs pass an infared beam through the sample and compare it with a known standard. This is an ok guess for soot, but for vehicles stored internal rust is an issue and a high TBN is in order. Fuel contamination causes viscosity changes too, I suppose you can smell for that, but my lab tests are 12 bucks and no shipping because it's on the way to work.

lurch59

Arco had a graphite oil, it was all the rage in the 80's I think, not sure if Mobil 1 ever had a graphite....

Not sure what you mean by the second question. Mobil 1 has a very good base stock. It's a true synthetic, which I like but admit it's probably not super important over highly refined base stocks. You got to look at the additive package too. That being said, it's a very good oil but not what I use.
. I would say it's in my top 3 picks.

lurch59

Response to Ldevalle-
You have hit the nail on the head. A good synthetic with a robust additive package may go on for a very long time, as long as the filters are changed and the additives are replenished by the addition of new oil.

Rdelvalle

My friend was referring to synthetic Mobil1. Their recommendation was 25K miles intervals.

GTOguy

A lot of good valid information here. A few guys on the Pontiac forums are using bypass filters and are racking up huge mileages on regular mineral based oils with virtually no degradation over many thousands of miles. One guy has something like 350,000 miles on his rig and changes the oil at 40-50,000 mile intervals. Had it analyzed and it came through with flying colors. Most folks with classic cars don't want to install all the extra (and unsightly) plumbing, but a bypass filter used in conjunction with the regular filter really keeps the engine oil up to snuff. They do actually work as advertised.

calwldlife

ok. thanks. arco it was then.
i remember when mobile1 was all the rage.
i also remember when some change took place to their oil
that many said ruined it? in other words was no longer the super stuff.

during that time, 70's, my cousin was in the navy doing oil wear testing to
find what the navy was going to buy.
havolin supreme was number 1.
castrol number 3
i switched to castrol and still use it today.
never tried mobile1.

Robert61

Lurch what you said in post 53 is EXACTLY my point. If you filter the oil enough it would last indefinitely. But none here self included probably are running filtering that would be necessary to accomplish this. And I hope you aren't suggesting these guys go out and find a filter that goes to 2 microns. With out increased filter capacity I'm pretty certain they would immediately burn bearings. While I don't think soot and fuel are the primary causes of oil degradation normal metallic wear is. And I think we would argue quite well with each other without a lot of the nd that ends up getting these locked. I had a urologist that is a major car enthusiast. He has several high end collector cars that I would never be able to afford. I only saw his son in my visits but he told me about his dad's collection.

davekp78

I wonder what engines they used. Roller or flat tappet? Fuel injected or carbureted? What period of time for the 100K miles?