larry47us

I just got my report back from Blackstone on my latest Used Oil Analysis. They had two comments:

1. They found a trace of fuel in the oil.
2. There was less wear indicated in this oil change than in the last one.

There were three changes between this oil change interval and the last one:

1. I used Mobil 1 5W50 instead of Mobil 1 0W40.
2. The oil change interval was extended from 3,000 miles between changes to 4,600 miles between changes.
3. Maybe (just maybe) I didn't drive the car quite as hard. I don't track my car, so this was just driving around town.

I don't know that you can draw any long term conclusions, but based on my experience, there is no reason to do oil changes every 3,000 miles. At least not on my car. I leave it to you to draw your own conclusions. Any comments are welcome. I have attached the UOA for your review.

larry

Macster

3K mile oil change intervals aren't for everyone.

I'm on the road this week and will be covering nearly 5K miles and no way the engine needs a 3K mile oil change. (The oil -- Mobil 1 5w-50 (not a typo for 15w-50!) was fresh when I left and will be changed after I return though.)

However, if my usage only put 3K miles on the car in a year's time, the engine would get an oil change every 3K miles (every year).

Sincerely,

Macster.

larry47us

Macster:

My oil weight wasn't a typo, I am using 5W50 in my car. Certainly, if you are putting lots of miles on your car, a short oil change cycle can become a real pain in the neck, to say nothing of the added cost!!

I think, though, that if I was only putting 3K on my car in a year, I would change the oil more than once a year. Whatever happened to those 3 months or 3,000 miles thresholds?

larry

Dock

Uh Oh, this might cause some to become apoplectic.

Dock

I go over one year between oil changes, with about 4500 miles accumulated. The oil checks just fine with Blackstone.

LVDell

The fuel might be the result of not driving the car after warmed up. When did you collect the oil? If you just let it warm up without driving it to temp, then that would probably explain the fuel in the oil.

larry47us

You know, Dell, I didn't think of that. Actually, I just let the car idle a bit to raise the oil temperature enough to get the oil flowing. Certainly the engine was NOT at full operating temperature when I changed it. I really didn't want to have to risk getting burned by the hot oil. Interesting thought, though. Maybe next time I'll do the full warm-up, and see if that affects it. But, now that I think of it, wouldn't the procedure to pull the fuel pump fuse before changing the oil, and then turning the car over cause any fuel in the engine to dump into the oil pan as opposed to being burned by the normal combustion process of running the car?

larry

LVDell

Not entirely sure about that fuse issue as I am not proficient enough in the mechanics of the fuel travel.

It just could be my senility, but I swear I read somewhere that Blackstone said to warm the oil up to temp by driving rather than idling to avoid higher fuel levels in the oil.

larry47us

Dell:

That might well be the case. Next time I'll drive it up to temperature. But I think considering that the slight amount of fuel in the oil was the only thing that they could complain about, I'm very happy. It is interesting to note that I had drain plug magnets in my engine between the last two oil changes, and in spite of the fact that the interval was 50% greater, the iron in the oil was 50% of the previous number. Was that due to the magnets? Sounds like a good reason to me. But, seriously, the iron level in either case was minuscule. Certainly neither level was something to worry about.

larry

LVDell

What were the pre and post iron numbers?

c32AMG-DTM

larry47us,

Interesting results. I've read that fresh oil has detergent additives that breakdown during normal usage, after which the oil is primarily just a lubricating agent.

Too-frequent-changes can allegedly result in an engine that only ever sees oil with detergents, instead of getting a break from them for a spell (with longer changes). And, allegedly, that may cause additional wear.

Not sure if your "less-wear" is from the change in oil, or the longer interval, or something else entirely... but it sounds like a good thing regardless of why.

PAULUNM

I don't believe that at all- I'd be interested to see where you've read this.

larry47us

I changed the oil when I first got the car, and then 3,000 miles later. The UOA iron numbers were 19 and 14 respectively on those two changes. At the time of the second oil change, I installed magnets at all 4 drain locations. The iron number on this most recent oil change was 8. Pretty surprising, considering the much longer change interval.

Maybe the magnets were working on a microscopic level? I dunno. But it is interesting that the number dropped so significantly, especially with the longer change interval.

larry

c32AMG-DTM

Mostly some forum chatter, with opinions on both sides, kind of like this:

http://www.bobistheoilguy.com/forums...1900212&page=1

Also, some references like this (of particular note - the 3rd bullet point):

http://neptune.spacebears.com/cars/stories/mobil1.html

A few other sites (esp. BITOG) reference the Ford and Conoco studies as well, along with the SAE paper. I suppose I didn't word my post well above, it might be factors other than detergents.

In the end, people can do as they please... I'm not trying to convince anyone of anything. One can change his oil every 1k miles if he wishes. I just found it interesting that while counterintuitive, perhaps, doing so might actually be worse for the engine than a longer OCI.

adam_

FYI-

You should drive the car for 20-30 minutes at temp, and park it. Then change the oil. You can do it when warm or the next AM. (Purists will claim you need to drain it warm...whatever.)

This will ensure you don't have fuel from the cold start. (The rich running at start will elevate fuel in the oil, but then will evaporate once fully warm.)

A