Reasons for clean oil?

[GasSavers_maximilian]

When I changed my oil this spring it was still quite clean, and I was curious as to the reasons. I only had about 2,500 miles on it since the last change (in Autumn - hit the 6 month change limit) which isn't a lot, and my car is pretty new (never owned a new one before), and I take it easy when driving. Which of those would be a factor? Are there any other causes? Trying to build my intuition for such things. Thanks a lot.

Oh, yes, I change my filter along with the oil.

[theholycow]

Most modern cars come with far longer intervals than 2500 miles. You're probably using synthetic. Your driving style may be a factor too.

You really don't need to do anything more than the manufacturer-specified normal use interval unless you've got some condition that's really particularly abusive. Manufacturers expect people to drive hard and be behind dusty dumptrucks on the highway; that's "normal". Severe service is driving two miles per day, racing, towing up and down mountains while exceeding GVWR, etc.

Do you know someone who followed the manufacturers normal interval and had some failure that could have been prevented by more frequent oil changes/better oil? I sure don't. I have yet to find a third-hand example, even.

In fact, I'm at 183,000 miles on my GMC, which has this history:

• While it was young, I ran it out of oil. There was a leak, and I didn't believe the "Oil level low" message when I saw it. I figured the oil level sensor failed. I don't know how long I ran it dry before I finally got it in for what I thought was low-priority service.
• I've usually changed the oil when the "Change engine oil" message came up, which tends to be 6,000 to 7,000 miles if it's driven daily. I usually brought it to a few different small mechanic shops, and sometimes Jiffy Lube. I've never specified what oil they should put in.
• Sometimes I procrastinated on the "Change engine oil" message for another 3000 miles.
• It's done its most heavy work on the hottest days of the year, towing my camper up Pennsylvania mountains when the ambient temperature was over 90 degrees at the top of the mountain. It's done plenty of fast driving, some off-roading, and lots of hauling, though the majority of its miles have been moderate or hypermiling driving.
• The last few oil changes I've done myself using WalMart SuperTech High Mileage 5w30.

Sounds like a recipe for disaster, right? At 183,000 miles, it runs great. It doesn't take a Toyota or a 3,000 mile interval to get 200,000 miles or more from an engine.

I had a 1997 Pontiac Grand Am with the 3.1L v6. That engine died an early death at ~130,000 miles with an internal failure of some sort (I wasn't told exactly what went wrong). I had changed the oil religiously every 3,000 miles, which was the severe service schedule. It was my abusive driving that killed it.

So, I have become extremely skeptical about the oil change myths commonly believed by most people and encouraged by the oil companies. Especially with manufacturers who have to cover 100,000 mile warranties, I find it hard to believe they'd tell you the wrong interval. They have little to lose by specifying a shorter interval, and a lot to lose if they have to replace one out of every 1000 engines.

[GasSavers_maximilian]

My recommended interval is 7,500 miles or six months. I hit the time limit. It's actually rather convenient since I set a repeating Google Calendar event to email me reminders every six months. Also means I can get through the winter without a change. It's still quite clear color had me wondering. All my older cars I did at 3000 miles and the oil was black. I'm actually not running synthetic. I had some oil already around I want to use up first.

Is six months conservative? What might be a more realistic time?

[bobc455]

Originally Posted by theholycow

Do you know someone who followed the manufacturers normal interval and had some failure that could have been prevented by more frequent oil changes/better oil? I sure don't. I have yet to find a third-hand example, even.

When I first acquired my 1969 Buick from my Grandmother, it had about 62k miles. The engine died at 67k miles, because of oiling problems.

When she owned the car, it was typically driven 2 miles on Sunday to buy the paper. Once in a while it would be taken on a long trip or something, but it sat quite a lot.

When a car sits a lot, moisture accumulates in the oil. And if it never gets hot, the moisture never burns off. Also, when the engine starts cold it runs richer, which means additional HCs become dissolved in the oil, which gets acidic over time. Again, if the engine never (or rarely) get hot, these don't get burned off. (this type of treatment is the reasoning behind the "three months" in the "three months or 3k miles")

In my case, in addition to the engine seals wearing out (mostly from being eaten away), the timing chain busted causing debris to go into the motor and its untimely (or un-mileage-ly) demise. Although the timing chain never actually broke, chunks of the gear got stuck in the oil pickup causing very low oil pressure, yada yada.

My grandfather actually used to work for Quaker State (in a non-technical position), so you can be quite certain they "did what they were supposed to" for oil changes. They had a good relationship with their local mechanic, and saw him frequently.

In addition to more frequent oil changes, the car should have been given more "excercise" - long trips for the engine to get hot and burn off the gunk in the oil.

To this day, there are many Buick 350 motors that haven't been opened since they left the factory, so I believe this was due to the way the car was treated and not faulty design.

So there's a first-hand account for you. (Well I guess it's second-hand for you.) But granted, this was an unusual situation.

-BC

[theholycow]

Hooray! I'm getting data! So, an engine built with 1962 technology and manufacturing processes failed prematurely (how long were engines expected to last in 1962?) with severe service as I describe - even worse, I said 2 miles per day, but that car was driven 2 miles per week.

The only other data I've ever got when I ask that question is this:
http://www.camaro5.com/forums/showth...475#post495475

i had a 91 4.0 explorer before the gmc & i drove it to 207k mi without a problem, but when i got my truck, i gave the ford to my sister & she ran it out of oil & locked up the engine.

So, now I've got two data points regarding stuff that even I would describe as severe. I've yet to see data for a modern engine that was driven normally and maintained per its schedule that died prematurely.

maximilian, I'd say you're a prime candidate for oil analysis. Send a sample of it off to be analyzed before changing it. With your usage patterns, analysis ought to pay for itself. Get it analyzed and change it only if it needs to be changed.

[GasSavers_BEEF]

I once waited 9 months before changing the oil in my truck. the kicker was that I had only driven it about 1000 miles during that period.

I had that truck for almost 5 years and it had roughly 17k on the odo when I got rid of it.

the oil never really looked that bad when changing it. it was a 2004 dakota purchased christmas of 2003

[Jay2TheRescue]

In my Buick I've put nothing but synthetic since the engine was replaced (about 13 years, 60,000 miles ago). Oil is changed once a year, and I never hit my mileage limit when I change it. The oil looks like dark honey when changed. It never gets black. Its always clear.

The oil in my 98 K1500 also never turns black. I don't know what was done before I bought it (Had 108,000 on it when I bought it), but I have used nothing but synthetic oil in it since I've owned it. I operate on a 5,000 mile change interval. When my odometer reading is divisible by 5,000 I change the oil. It never turns black, and is always translucent as well. The truck was probably serviced at the dealer since it was new, because I bought it at a GMC dealer, and it was a local trade. Dealers usually don't sell used vehicles with over 100,000 miles on them, so they must have known about its previous service history, and felt it was a good vehicle.

-Jay

[Jay2TheRescue]

HC - I also knew a guy that never changed his oil. He would top it off when it ran low, but never changed it. When I last saw him he had nearly 200,000 miles on his Chevy K1500.

-Jay

[dkjones96]

Of cource you don't need a Toyota. And just because it is a Toyota doesn't mean it'll be good. A friend of mine bought a 2002 Corolla with 85k miles on it and it goes through oil like mad. I was following her one day and it looks like bad rings. American cars might get a bad rep for quality but pretty much none of those pushrod engines have killer problems and most, if not all engines built after the 70s should be good to 200k. The v6's had a run there with intake manifold leaks that could ruin the engine left unattended but other than that...

Not surprised to hear a 1969 engine died at 67k. They had better machining then than they did in the 40s where engines routinely needed rebuilt every 30k miles but it wasn't anything like the advancements made in the late 70s and 80s. Plus, people have the tendancy to never do ALL the maintenance a car needs. Change the oil and call it done is good now, but not on a 69' with a carb. Fuel wash is a *****.

My oil has stayed pretty clean. I've been shocked that the amount of oil in the engine hasn't moved a bit in over 2k miles(still just a hair over the max line on the stick). I use Supertech (Walmart brand) oil filters and always recommend them. Not only do I use one of the best filters on the market, I buy an over sized filter that looks to have 50% more capacity than the stock recommended and run Mobil 1 10-30 with 5k changes so far. I plan on changing the oil every 10k when I get to 50k miles(next change) as the oil is looking like it'll be pretty clean at the end of this cycle.

[theholycow]

My VW's schedule says 10,000 miles and requires oils that have been approved by VW, which may be a stringent test. I use hard-to-find Castrol Syntec European Formula 0W30. After 10,000 miles, it comes out black but not sludgy, gritty, or inconsistent.