posted
"Depending on driving conditions, you could probably go past 3000 in many cars. And with synthetics, you can usually go to 10,000, though most car companies in the past have not recommended that."
You could, but why? From what I've seen, after 3000 miles there is a dramatic change inside the engine. Before that, the oil may discolor, but after 3000, the metal parts begin to be coated with a slime that is actually particulate from blow-by. What happened in the mazda was that the particulate reduced the clearance in the bearings, until they clamped solid, and snapped the camshaft. That usually happened at around 7000 miles.
But that's catastrophic failure. In the meantime, you're accumulating shmutz in the ring lands, the oil galleries, and valve guides, that at the least changes tolerances, and at the worst is abrasive.
My rule of thumb is to change the oil at 3000 miles, but if I don't get around to it, I absolutely change it at 4500 miles. That's as far as I'll go. Oil changes are cheap, engines are expensive.
As far as cleaning the EGR valve: from what I've seen, EGR valves usually fail because of high temperature galling on the valve stem. It is exposed to exhaust gases after all. I imagine the passages could clog with soot if the fuel isn't burning right, and that would be worth cleaning out. I've never seen it happen, but I'm sure it could.
Posts: 3735 | Registered: Mar 2002
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posted
In my owner's manual for my Pontiac it recommended 5000 and absolutely not past 7500.
I usually changed it around 5000-6000 miles and put over 128000 miles on it with nary an engine problem, ever. We got rid of the van because the transmission went out, but the engine still ran like a dream. I think the 3000 miles is a conspiracy by the oil change companies to get me to spend more money with them.
And oil changes aren't cheap, unless you do it yourself which I just don't have the time or expertise to do.
Posts: 14428 | Registered: Aug 2001
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posted
Oh my. First: When I was in Virginia, I had that same problem (gas cap loose). However, since I am now not able to read the computer using a paper clip anymore, I had to take it in. The mechanic came out with his computer, plugged it in, and read the code. We tightened the cap and the code cleared. He was also kind enough to ummm delete the history (He asked and I said to do it). Which, at least in the area I lived in, was illegal to do.
Second: I agree with Glenn on the oil issue. Viscosity of the oil is the first thing to go over time (and metal shavings doesn't help any). I however, do wait till about 4000 miles to change the oil. I use Valvoline Durablend and FRAM oil filters. I use nothing else.
Oh, and uh, I have had my oil changed at a dealership (They were doing a safety inspection, required by law in VA) and it cost me a whopping total of 20 bucks.
Posts: 2208 | Registered: Feb 2004
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quote:In my owner's manual for my Pontiac it recommended 5000 and absolutely not past 7500.
Yes, but if you read further, you'll note that the driving conditions mentioned by your manual would mean that you'd have to drive like a grandma everywhere in order for this to be necessary. We're talking no hard accelleration (like coming out of a toll booth and trying to merge into traffic), no long trips, no nothing. It's rediculous.
Normal driving requires you to change the oil at 3000 miles. In fact, my GM owners manual for my Cavalier recommends changing the oil at 5000 miles, but then gives a list of driving conditions that, if met, necessitate an oil change at 3000 miles (like driving in cold weather... Hello! I live in WISCONSIN!).
It's not some kind of lame conspiracy. If you've ever changed your own oil, or even watched somebody do it, you'd notice the huge difference between new oil and old oil, and the difference between oil changed at 3000 miles and oil changed at 5000 miles.
Posts: 4753 | Registered: May 2002
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posted
Well, the speed limit is seventy, so eighty is not unreasonable considering that there's virtually no one around and the few people I see pass me doing ninety.
Posts: 1751 | Registered: Jun 1999
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posted
By the way, I'm talking as a former ASE certified Master Auto Technician.
The difference I've seen is not in the oil, but in the residue I found in countless engines as soon as I pulled off the valve cover. As soon as the car hits ~3000 miles, that residue begins accumulating.
Prior to that, the metal is actually clean. The difference is very noticeable, but most people don't change oil often enough, or in enough cars, to really be able to see the difference.
Posts: 3735 | Registered: Mar 2002
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