robsayers

So I'm doing an oil change today. I bought 5 qts of oil as my manual says I should... go home, jack up the car and drain the oil. Not long after I do this, I notice the oil is draining pretty slow, so I assume its because the car is tilted... I lower the jack and and at this point I'm called away for a bit. I get back, replace the drain plug and notice not much oil at all is in my drain pan. I didnt really know what to do, so at this point I just replaced the oil that was drained and put the new filter on. Total, after it was all said and done, it only took 3 qts of oil. Shouldnt it have taken more? Where might the other qts be hiding? Thanks.

peejay

Always change the filter first.

You will never get all six-seven quarts out. Best you can hope for is four, maybe five.

GavinJuice

Your oil cooler. And what would be the reason for changing the oil filter first?

peejay

Take a soda bottle, fill with water and cap it, flip it upside down, drill a small hole in the bottom. Flip it upright, the contents won't leak out. Too much surface tension to allow air in to let the water out.

Now uncap it. Water now dribbles all over your leg.

Applied to the current situation:

The bottle is the oil passages, the hole is the bearing clearances, and the filter is the cap.


I have always changed filter first ever since when I was a rookie mechanic and I noticed that, no matter how long I left a car sitting with the drain plug out, no matter how long it's been since even a drop came out, a bunch of oil would come out as soon as i unscrewed the oil filter.

Siraniko

iTrader: (13)

And always pour new oil in the filter prior to installing it.

Directfreak

iTrader: (2)

How do you do that AND Not get it all over the pedestal at the same time when putting it back on?

(with the exception of a Remote mount Oil Filter)

---------------------------

When removing an old filter, I always make a hole in the filter with a screw driver 1st, so the oil will drain out the filter, and not spill when I actually unscrew it.

GavinJuice

I don't think it has anything to do with suction, or surface tension as you suggested. You made it much more complicated than it is. You ask anyone, or go to any site on how to change your oil and it will tell you drainplug then oilfilter. You drain your oil and the same time allow the oil in the filter to drain, seen as how there is now nothing to prevent it from flowing. No your not going to get every drop from your oilfilter, but what the heck is maybe 1/2 a cup of oil when we still have almost 2qts of oil remaining throughout the engine? And plus you crack the oil filler cap to allow the oil to flow better. I think any oil you see because of your surface tension relationship, would be because A your filter is absorbed with oil to begin with or B it has to escape through a 1/2" hole through whatever media is contains.

Yea it's always a good idea to fill up the filter before you put a new one on, but it makes it a bit complicated when your filter is sitting almost straight up and down.

hornbm

jesus crist, just punch a hole in the oil filter before you drain the oil and be done with it

Siraniko

iTrader: (13)

[QUOTE=Directfreak]How do you do that AND Not get it all over the pedestal at the same time when putting it back on?

(with the exception of a Remote mount Oil Filter)

---------------------------

All you have to do is cover the primary hole with your fingers, quicky turn it upside down then twist on to the pedestal. It takes lots of practice. I just never been a fan of starting an engine with empty oil filter. Something I learned the hardway from my mentor

robsayers

I forgot to mention it, but I did that as well

Pele

iTrader: (28)

On every oil change I do, I have a habit of disconnecting the ignition system and cranking the engine for a few seconds, once the oil has slowed to a dribble to remove the old oil from the filter and passages...

I also usually have other things to do when I change oil, so I go off and do other things while it's draining... Either that, or I go inside and have lunch.

I've always gotten almost all of it out, short the 1 quart the engines either burned or leaked over the course of the past oil change interval. The filter's usually bone dry by this time.

I also get to see that the low oil level and low oil pressure sensors are working as I do this.

Then I always crank it for a few seconds to pump the oil back into the filter and passages after I've filled it before reconnecting the ignition system.

Rex4Life

Now that's a new trick (to me)--damn why didn't I think of that. Thanks for the advice. Scott

Jeff20B

iTrader: (13)

I never sweat the oil that always remains in the engine (rotors, oil cooler). It's one of those features that assures there will be enough oil in the engine when it fires up. The good thing about rotaries is that they don't fill their oil with nasty contaminants like boingers do. I think all we've got to worry about is our oil getting diluted with gas. More so with a port job. I enjoy it.

Pele

iTrader: (28)

Contaminants like what?

Both types of engines have blow by... Both types have wear components... I don't see how they're different.

DAVID GRIMES

From what I've been reading, alot of us rotorheads are the ones with the contaminants ( stuff Mazda never intended to be used ): MMO? ATF ? 2 cycle oil ?

Aviator 902S

Combustion products (carbon, etc) are the contaminants in question. In boingers, blowby goes past the rings and into the crankcase, contaminating the oil.

In our (superior design) rotaries, blowby goes out the exhaust ports and/ or into the adjoining chambers created by the rotors and housings. Result: the oil stays cleaner for a longer period of time and doesn't break down as quickly as it would in piston engines.

And if your engine becomes flooded, any fuel that may get past the side seals and into the oil gets evapourated off the next time you run the engine for an extended period of time, ie: an hour or longer, preferrably at highway speeds.

Myc1972

When i changed my oil i also niticed that i didn't use up the 5 quarts i had bought
to refill my engine. Later one of the guys from the forum told me that i should have
turned the engine by hand to drain it completely, while the plug was out, and the filter was removed.


Hope this helps!

Myc1972

robsayers

Wow, great info in here. Thanks for the replies everyone.