cjstringer

WOW! You actually pay someone to do your oil changes? I do a full synthetic change every 5k for under $25 with filter.

If I were using regular oil, I could do it under $10.

Try doing it yourself, you'll save a ton of money. It really isn't that difficult.

And I thought I was lazy......

jaredspangler

European ACEA A5 and B5-02 are standards much like our API and ILSAC classifications. Almost all synthetics and some dino oils in the US meet that specification. It is Europe's specification for what we would consider extended drain intervals. The spec calls for 10,000+ mile service life. So if some oils meet the standard like Mobil1, why are they still trying to push the 5K oil change? Answer - Money makes the world go round. If they can pull more money out of your pocket, they will.
Dirt entering the engine is not the reason you would need to change your oil before 25K. Even most dino oils could support that. The real reason is gasoline entering the crankcase via blow-by, coolant entering from small leaks, and water from condensation and blow-by as a combustion by-product. These combine in the crankcase to dilute the oil, and create acids that break down the additive package. Oxidation of smaller oil molecules also creates problems as well.
Oil should be change when it needs it. Some advanced vehicles have oil change sensors in them, some so advanced they actually sample the oil for temperature and chemical content, apply the results to a logarithm establish by the manufacturer, and tell you when it nees to be changed.

P5er

I've been using Amsoil 5-30 full synthetic and after 4K miles it needs a change, engine becomes noisier and less smooth even my auto tranny shifts less smooth! Along with a PureOne oil filter, I will switch bo a bigger V6 filter maybe it will be good enough for 5K.

Don't belive in 25K miles, our cars take only 3.25 quart @ $5.40 per quart with a $5 oil filter that's very cheap!!!

I using Mobil 1 ATF in my tranny and Waterwetter as a coolant.
Mobil1 ATF in power steering and Valvoilne Synthetic DOT3/4 braking fluid.

So far 33K of trouble free miles on my 2002 P5

tec-9-7

Mobil 1 used to be advertised as the 'once-a-year-oil-change'. They would say in advertising that you change once, then replace the filter and add a quart every 3K miles. I agree w/ those here who suggest longer intervals. Oil companies and dealerships will try to convince you to change every 3K miles. Mazda says you only need to change every 5K miles under severe conditions.

I live in FL (high humidity/high heat) so I follow that schedule with dino oil.

3K mile oil changes were a good idea back in 1962, but w/ modern engines/manufacturing tolerances/oil additive packages they are a waste IMO.

Paul

ZiO

You are still getting sand/debris in your engine... the oil itself may last longer, but there is still particles getting into your engine that wear away at the internals... the longer you keep that ouil inthere, the more sand accumulates and becomes hard on your engine. Maybe if they have better internal engine parts, then they can withstand more than other engines. Yes, i agree that changing every 3K is too much, but no way should ANYONE be changing past 10K miles. I wouldnt recommend it.

Sil_Pro5

Oh my Lord youre kidding right? What do you think the oil filter is for? And remember what I said about having a UOA done? It tells you how much silicon is in your oil and that tells you whether you have a leak or not. ANd BTW, the amount of dirt (silicon) that gets past your air filter (a stock element) is neglible unless of course you have a K&N. DOnt believe me? The UOA's speak for themselves.

Farsyde

i still use dino oil every 5k miles. When i drain it i let it filter through a fine filter (looks alot like filter paper but bigger pores) and if it is loaded with garbage i shorten the next interval and change out the air filter cuz there is sooo much dust here. My next carwill prolly get the synthetic treatment though.

Scarmiglio

By the way, there's actually a lot of HP in oil. If you drain the oil out of your engine, your car will lay down more horsepower on a dyno. Your Crank Shaft spins around and keeps smacking into the oil (thus splashing it all over your engine - which is necessary), but every time the crank hits the oil you're losing power. If you use a lighter weight oil, there's less resistance on the crank and you will get more power. Advanced sports cars (and those who install conversions) have systems don't have a traditional oil pan and instead spray oil on to the crank to reduce oil drag.

SilverPR5

I thought I would pip in here and let you know something I researched about Amsoil.

My sponsor has been using Amsoil for years now in his truck. Back of the bottle says 35,000 mile oil changes can be done, you just have to change the oil filter every 3000 miles or so. He left his Amsoil in for 40,000 miles and then took about 1 ounce out to get it tested by http://www.titanracinglab.com/ The results came back that his oil was still good for use.

I started using Amsoil in my Civic and notice better mpg, acceleration and smoother idle. And most companies will tell you to change your oil at 3000-5000 miles because heck they're making more money. Even Mobil 1 Trisynethic you don't have to change every 3000-5000 miles. Talking to many racers some say wait til 7000-10000 miles - just making sure you change the oil filter.

kc5zom

I pay thirty bucks a change to have a Mazda OEM filter installed and 3.75 or whatever quarts of Mobil1 added, they even wash the car while it is there. I do this every 3750 miles for one reason, that is the same interval as the tire rotations (and my tires look brand new even with 20k on them). It is a little more money, but an oil change is good for your car no matter what interval you do them and it is convenient to have it done when the vehicle needs to be serviced anyway. Besides the fact that I usually run relatively high RPM's most of the time (can't find the off-button for my right foot yet). I generally shift around 4k (gas mileage is **** by the way) and I like the added degree of protection a synthetic provides against me wearing out the motor. I also run a synthetic transmission fluid, but only because Mazda told the dealer to put it in when I was having synchro issues in second gear. I felt better power from both, and the engine definitely runs smoother.

ZiO

Relax, I am not disagreeing with your previous essay. But you do realize there are limits to both filters. And if you think that it is negligible, then leave your oil in your car for as many miles as you want. If you feel 25K or 50K intervals are good, then do it. But apparently you are saying that there should be no difference in changing your engine oil whether you drive on gravel roads everyday or just city streets. Its up to you. I'm done with this thread.
Thanks.

JonKlsn

What about living in an extremely hot climate? PHX AZ here. I just had synthetic put in my car. Most mechanics here say that cuz of the extreme heat, plus all the dust we get here, its wise to change oil frequently. Anyone know if that is still a worry with synthetic?

tec-9-7

Couldn't help chuckling at this. When I had my Prelude (97) I would normally shift around 6K ( tho I'd go up to 7100 when racing)...

Paul

Farsyde

the amount of crap that gets into your engine and stays in there is dependent on the airfilter and oilfilter. Synthetic should be fine in extreme climates b/c that is what it is designed for.

kc5zom

I find that if I lay off and let it rev only to 3-3.5k I get much much better gas mileage. But right foot will not comply, unless I look at the gas gauge and it is almost empty.

But with a Prelude you also have to rev the hell out of it to get any power, the Pro has pretty useable power after about 3,500.