I'd agree with you have a problem - but not necessarily a SERIOUS
problem. A car can still pass e-test and not harm the cat with
consumption of 1 quart per 1500 miles (which used to be considered
On Wed, 24 Aug 2011 22:02:32 -0400, Metspitzer wrote:
I use Pennzoil 5w30 in a Trailblazer with 90k on it. Every 3k miles since
the breakin oil was removed.
Recently had the plugs changed, first time since new. Compression test
each cyl. All 6 (4.2L inline 6 Vortec 275 HP 10:1 compression ratio)
were within factory specs. Also use a Fram high density filter.
Oil pressure is 41 PSI at hot idle, 70 PSI at 2k rpm. The motor is so
quiet it's hard to tell if it's running. The factory 'change engine oil'
light comes on each 5k miles after reset. As far as I'm concerned that 3k
oil change rule is worth following.
My Buick was the same way, except I changed oil at 7500. In the 130,000
miles I had the car that would be 17 oil changes. Following your method,
I'd had had the oil changed 43 times and the results are the same. At $30 a
pop, I'm $780 ahead.
I imagine I could have kept it longer, but the car had other issues and I
gave it away to may grandson. Damned engine ran perfect though.
I've also owned a couple of Sonatas. The dealer (I don't use dealer service
in general) recommends fuel injection service every year for $129. If I did
that on all my fuel injected cars in the past say, 20 years, I've have spent
thousands of needless dollars. I've never had an FI problem. So, 2 cars at
$129 for 20 years, the shop would have $5100 of my money and I'd have no
Preventative maintenance is important, but should be done with sensibility.
Click and Clack call FI cleaning 'wallet cleaning'. Unless the engine is
running crappy, the injectors are already clean enough. Yeah, I know,
the computer compensates up to a point. Trip odometers are wonderful-
reset at every fillup, and if there is a change in MPG, it should jump
right out at you. When mine starts drifting down half an mpg or so, I
know it is time to dig out the compressor and top off the tires.
dirt. The basic design of the engine has not changed. Aluminum
bearings (basically) aluminum pistons, and cast iron crank and
cylinders. Oil gets dirty., doesn't matter how much the oil costs, or
how fancy the vehicle is. The oil still gets dirty in about 3000 miles.
(given an approximate 5 quart capacity). Larger sumps can go
remove the "not" from my address to email
The big killer is combustion byproducts. Since engines are a lot cleaner
burning than they once were, this is reduced somewhat. The manuals on my cars
recommend 7500mi for light service and 3000mi for severe duty. Look up the
meaning of "severe duty" and it includes pretty much everything except
non-stop interstate driving in 70F, dry, weather.
This is true! Or 'light service' could be described as 7,500 miles, all
run in one 'trip', on a dyno, mounted in a clean room. Not 'real world
Rant mode on:
Modern conventional oil's don't 'break down' in short trip usage, but
rapidly becomes more and more contaminated with water and acids...
leading to bearing deterioration, sludge issues, and hardening of seals.
Note that modern oils are still wonderful lubricants even after being
run well beyond their recommended change intervals... it's contaminates
that are the issue. (Dirt becomes more of an issue if the oil is run
long enough cause a filter bypass to open, or if you get a bum oil or
air filter. Modern oil and air filters are for the most part very good.)
If your 'average' trip is on the order of more than 20 min or so, oil
will routinely reach sufficient temperatures, and maintain them long
enough too boil off most (but not all) contaminates. These are
eliminated by the PCV. For 'long' trips, yes, 5 or 6 thousand miles
change intervals are fine.
But if your normal usage is short (or dusty) trips, contaminates rapidly
become more and more concentrated. It's here where you should do changes
every 3,000 miles, OR 90 DAYS, which ever comes first! 90 days as in
actually marking it on the calendar, and ignoring the odometer unless
it's racked up over 3k miles!
Remember, that water and acid are continuously at work, even when the
vehicle is just sitting parked. (Expensive synthetic oils contaminate
just like conventional's by the way.) 3k change intervals also minimize
dirt issues in the event you happen on a a bad oil or air filter too...
it happens on occasion.
If you don't care about the car, or trade every couple of years, run it
as long as you want! On the other hand, you can get a LOT of dependable
service out of most any engine by regularly changing oil. (Do the
coolant every year too... that's a rant for another day.)
Four oil changes a year isn't that big a deal...
Rant all you want, but the truth does not bear you out. Yes, some people
should change at 3000 miles, but most would be wasting their money. Some
others should change at 5000 miles. I know of plenty of cars in the
100,000 to 200,000 mile range with no engine problems at higher intervals.
The people that warranty my engine for 100,000 miles would not tell me to
change at 75000 miles if it was going to cost them money.
Sorry, you were right 40 years ago, but not in 2011.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.