Hi,

I had 2 friends with decent automotive knowledge help me out with my car's 2nd oil change. The dealer did the first one free because I went to the "getting to know your car" thing they do.

One of my friends did his car first to show me how to handle the drain plug, filter, etc. He was jealous when I showed him the positions on the subaru :)

Then we took the oil cap off of my car, and spent the next 5-10 minutes jacking it up, putting it on stands (needed to rotate the tires), getting water, etc. Then I attempted to remove the drain plug.

What happened next is best explained by the term "oil grenade". Very high pressure oil shot out and filled the top of the drain in < 3 seconds. The oil took awhile to drain down the hole in the drain and was pretty frothy. This was not the smooth oil drainage I had just seen on my friends car. Both of my friends seemed to think this was abnormal because we had taken the cap off to relieve pressure.

The rest of the change went without incident. However, they both suggested that perhaps the dealer overfilled the car at the first oil change.

I didn't get any CEL/oil idiot lights. However, engine braking is much smoother now and overall the car feels smoother. Probably just a placebo from doing my first DIY oil change. I have three questions:

1. Are the events indicative of overfilling or something else?

2. What effect, if any, would overfilling the car have?

3. Are there other ways to relieve oil pressure? Hot oil splattering wasn't fun.

Thanks
-Jason

The oil pressure is due to gravity -- can't change that. You can try not taking the oil filler cap off first. The Subaru has a bigger-diameter oil drain hole than most other cars, so the oil will flow out faster. Get a really big drain pan, one without the top with the little drain hole in it -- just a deep pan with a pour spout, and be ready when you take the drain plug out.

Ok, I understand that gravity will cause it to have some pressure. That's pretty self-explanatory.

However, I don't understand how gravity would cause my friends nissan to come out in a nice stream and also cause the subaru to explosively evacuate? Is there something unique about the engine design that causes that much pressure to stay in the system?

I'm just trying to learn if this is something I just have to deal with or if there are ways to prevent it. I've watched lots of folks change their oil and I've never seen the amount of pressure that I saw yesterday. Ditto the two folks that were lending me a hand.

Thanks
-Jason

Jason, For a nice neat oil change try the Fumotovalve, especially the model with nipple. Just slip a length of rubber hose on the nipple, drop the other end in your drain pan, flip the locking lever open, wait til it's done, relock the lever, pull the hose and you're done! You can do a search on this forum or look at www.fumotovalve.com to find the right application and order. Money well spent!!!

Glenn O

Glenn,

Thanks for the info. I've looked at those before and my only concern was the small amount of oil left in the pan due to the threads being a touch long. For $25, however, I might give it a shot and see if using a crush washer with the valve and its washer would help in that area.

Thanks
-Jason

Don't think you'll regret it! The very small amount of oil folks are so concerned about is ludicrous! This is a quality product, and anything that eliminates contact with hot, carcinogenic oil is a plus in my book!!:D Go for it!!

Glenn O

The Subaru has a bigger-diameter oil drain hole than most other cars, so the oil will flow out faster.
Also, if your oil was hotter than your friend's, it would flow out faster, too.

oil frothing is one sign that the oil has been over filled. cuz it's over filled, the crank will whip the excess oil, like whip cream and a batter

as for why u had so much pressure build up, still thinkin :confused:

There will be no pressure build up, it's just sitting in the pan, my guess is it was hotter than your friends. If it was frothy possibly it was overfilled but I think just hotter. It comes out like gang busters when it's nice and warm.

Thanks for all of the replies.

The temps should have been about the same. We drove the same distance to the house we use for working on cars. He moved his into the garage right before the change and his car sat about 3-5 minutes before moving.

Mine sat for 15-20, then I moved it away from the curb (driveway had a bad angle) so we could get it level to rotate the tires. I've noticed that the 2.5L retains a lot of heat. My old civic would be cold after sitting for 30 minutes or so, the subaru takes a lot longer. Maybe the Sentra my friend owns is the same way.

I was probably lulled by the smooth stream that came from the Sentra that took its time to empty. Next time I'll be expecting the subbie to dump all of the oil in 5-10 seconds. I'll probably also look at the fumoto valve. Anybody with one bother to empty the pan with the valve and then remove the valve to get the residual oil out of the pan?

-Jason

I did there was only about 8-1o ML is all, I notched the first 3 threads of one valve.

Try pulling the dipstick next time. This would surely relieve any pressure differential. And ya, It does come out of there quick. I agree that the drain hole is larger. What I do is loosen the plug till she's about ready to let loose and then check to make sure i've got the pan correctly aligned (accounting for the streams force and parabala accordingly) and then i'll let-er-rip.
The fumoto valve can be slotted. I would not recommend this to the unexperienced, But it is not too tough.

Originally posted by jcooper138

However, I don't understand how gravity would cause my friends nissan to come out in a nice stream and also cause the subaru to explosively evacuate? Is there something unique about the engine design that causes that much pressure to stay in the system?



I just went from a nissan to my new WRX. Did my first oil change on it last week, and the oil plug is a whole lot bigger than the one on the nissan is. Because of this it came out a lot faster than I was used to with the nissan and it got a little messy since I wasn't expecting it. So I'd have to think this is pretty normal, except for that frothy oil part :confused: I didn't have that when I did my WRX.

-Bill

Also on the fumoto valve....how exactly does it keep you out of contact with the oil since you have to change the filter as well?:confused:

Call it luck or whatever you want, but getting oil on myself when changing my Subie's oil is almost non-existent. I've changed my oil in church clothes, before church. You don't have to worry about the oil filter getting oil on you because it's mounted vertically and easily accessed. Just keep it nice and steady b/c, yes, it is full of oil and if it slid in your hand it could drown you.

-Charles-

You don't get oil on yourself when removing the filter can be done a number of ways, the easiest two would be punching a hole at the bottom of the filter to drain it before removal, and the other easiest way is to loosen the filter so you will be able to unscrew it with your hands, then use a plastic bag to unscrew and catch the filter and oil. I use the bag method.

FYI, subaru's do have the biggest drain bolts, 20 x 1.5. The next biggest size I know of are some Toyotas and Mitsus with 18 x 1.5.

Sorry, not the biggest drain bolts :)

All of my Alfa Romeos have a 22 x 1.5 drain plug. I believe some Audis use up to a 26 x 1.5 drain plug.

All of my Alfa Romeos have a 22 x 1.5 drain plug. Dang, there is always someone else out there who is bigger, faster, stronger.

-Charles-