Oil change recommendations?

[whatthe]

I've seen some long term tests with Amsoil and Mobil 1 showing the oil was still good at 12-15k miles. There was a guy with a Camaro that sent the samples in at regular intervals even.

If you keep the oil in, just change the filter every 3k miles and you should be fine. The scariest thing about long interval oil changes for me is how the filtration abilities drop off over time if you don't change the filter. This will depend on what type of filter (i.e. depth type don't clog up quite as bad over time, but don't as high filtration capabilities early on).

I ran Amsoil to 20,000kms in one of my GTs years ago. The bearings looked brand new at 225,000kms after taking the engine apart to do some head work for turbo.

For Dino oil, I prefer Castrol.

If you do some google searching, you'll come accross lots of oil filter studies and oil studies to reference.

[nascarnation]

Originally Posted by Krieg

Have you noticed much of a FE improvement since the switch?

I don't have good mpg data prior to the 5W20 oil, although it's been in the family for all 133,000 miles, mostly driven by my kids who have grown up and moved on to their own cars so it's back to me.

Personally I would be very surprised if 5W20 made a difference big enough to measure accurately without a chassis dyno and controlled environment.

The last 8 tanks (approx 330 miles each) have ranged from 33 to 36 mpg (it's an automatic). Using the AC is a much bigger variable on FE for a small engine car I believe.
Back in May there were days when I used no AC, then in June, AC on the way from work, now in July AC both morning and afternoon.

I always cringe when I see somebody on the net write "I put in XXX oil and got 2 mpg more"
I guarantee that any auto company would do that tomorrow if they could prove it on the EPA test.

[Krieg]

Ummmmm.... why do you think that Honda and Ford use 20 weight oil? Mileage and emissions. ULEV status is in part due to 20 weight oil.

Honda does make compromises in order to get that awesome gas mileage. 20 weight oil is one compromise.

[Krieg]

You know, the first couple of oil changes on my Acura Integra, driving out of the oil change place, the car felt stronger.

I don't doubt that switching to 20 weight oil makes a measurable but very small difference to fuel economy. 2 mpg sounds high, though.

[Bror Jace]

As oil is used by an internal combustion engine, it picks up wear debris, unspent fuel and other contaminants (dirt in the air) and loses it's ability to lubricate. When tested, it's coefficient of friction begins to rise.

So, running oil an extra thousand miles or two may hurt your fuel economy (along with promoting engine wear).

[rjacob]

Okay, I took may car to Honda this morning and had the oil changed. I asked the guy about what kind of oil they use, and he said Mobil. I asked about synthetic oil, and he said they don't recommend them. He said they have them for one or two cars that are supposed to use them (he thought the S2000). But he said for most cars, it's just a waste of money. I notice on the invoice they used 5W20 oil.

One thing they did though was to let air out of my tires. I had them at 38psi cold pressure. Now I have to ecoinflate them back 38psi (AAA says hyperinflating your tires is bad, so I ecoinflate them).

[IndyIan]

I'm not an engine expert but FWIW.
If you are pulse and gliding using big throttle openings and low rpm you are loading the bearings in your engine more than the average person. Also oil pressure at low rpms can be lower than at "normal" rpms. Plus if you are going to thinner oil that is less able to keep bearing surfaces apart you might have a recipe for trouble. You are creating the toughest environment for the oil to work at.
Also the first number in oil weight tends to be the base oil weight and the second number is achieved through additives which can break down leaving you basically running with the base oils weight. So your 0W20 may be just 0W0 after some amount of miles.

So 0W20 oil run for a many miles at high load, low rpm situations may result in scuffing a bearing which could be a career ending injury for your engine.

I second the oil analysis to find out for sure how the oil is doing over a longer change interval, just to be safe because you'd have to save alot of money on gas and oil changes to pay for any type of oil related engine work.

Ian

[jonr]

Believe it or not, engine wear and friction goes up when you first change the oil. So you don't want to change it too often.

Various studies show this, but this is the only one I find right now.

Valvetrain Friction and Wear Performance with Fresh and Used Low-Phosphorous Engine Oils - Tribology Transactions

Re 0w20 oil, why not give some room for degradation and use 0w30?

[othergames]

Most engines, when the oil is changed at reasonable intervals, will outlast the other parts of the car. This is getting to be like the "eggs are good for you/eggs are bad for you" argument. An apple a day keeps the doctor away, but eat too many and you'll get stomach or colon cancer.

Change your oil to extend the life of your engine, or change it if you want to damage it.

[nascarnation]

Originally Posted by othergames

Most engines, when the oil is changed at reasonable intervals, will outlast the other parts of the car.

excellent observation
but remember there are other forums where 20,000 OCD afflicted folks argue argue over parts per million results from their oil analysis.............