Changing fluids in a vehicle

[Jordan Baker]

I’m getting my Jeep ready for the season and I was going to be using the Royal Purple oil in the transmission. It got me thinking, how does one change over the oil. I see the term “flush” being used a lot. However what does one actually flush the old oil out with? Or do you just drain the old and then pour in the new?

[David Dunlop]

Jordan.

Years ago I flushed out an M38 I had and used a gallon of kerosene to do so. I may still have the info downstairs. I will go check and get back to you.

David

[David Dunlop]

Back again.

When I first drained the oil, a lot of sand came out with it, so first thing was to drop the oil pan, clean it and reinstall with new gaskets. I left the drain plug out and poured in the gallon of kerosene. A fair bit of crude washed out into the catch pan. I then reinstalled the drain plug and added new SAE 30 oil to spec. Pulled the plugs and cold cranked the engine a couple of times for about 10 seconds each. Reinstalled the plugs and fired it up. The exhaust smoked briefly a bit and then ran clean no problems. Not sure the procedure was technically correct but it worked OK.

David

[rob love]

With the old non-detergent oil, you actually removed the pan like David did and cleaned it out. But with today's detergent oil, unless you are only driving it 4 blocks to church each Sunday, the oil should be cleaning the system out without the sludge buildups of yesteryear.

I would suggest draining the oil right after shutdown, while any particulate is still suspended in the oil. Open the filter cannister, remove the filter, and suck out the remaining oil from there with a suction gun. Follow up with lint free rags or towellettes to clean out the filter canister.

Once the oil had drained, and things have cooled off a bit, run your little finger into the drain hole and see how much sludge is on the bottom. If negligible, then put the plug back in and start re-assembling. Otherwise, pull the pan and start cleaning.

Pan gaskets are only about $10...far cheaper than those gallons of solvent or kerosene you are going to dump down the engine, and still not get it all.

Because of the removal of the zinc additives form today's gasoline grade of oil, you will want to run either diesel grade oil, add an additive like ZDDP to regular gas grade oil, or you could also likely get away with the high mileage oil from Cdn tire.Personally, I run multi-weight diesel oils like 15W40 and 10W30 in my engines and have had no issues. But if you want to live in the past, with the problems of the past, then go find some non-detergent 30 weight and have fun. The DND was running multigrade 15W40 in the Jeeps (and pretty much everything else too) when the Jeeps were disposed of.

[Jordan Baker]

Ok thanks for the advice. I’ll be draining and replacing the oils this week.

[rob love]

Pan gasket from NAPA:
Part:
FPG OS4350AD Product Line: FEL-PRO Gaskets
List price: 22.66
Your Cost 15.44

The same gasket from Rock auto ranges from $4 to $7CDN. It's the kind of thing you order a couple of when you are ordering other stuff and keep it on the Jeep shelf.

[Wayne Hingley]

Hi Jordan. When I "flushed" my transmission and transfer case recently, I drained the hypoid, and refilled with ATF. I drove it up and down the road a couple of times (shifting through all the gears), and then drained the ATF immediately while everything was in suspension. The ATF is very fluid, so it gets in all the small places and drains quickly (hopefully carrying much of the contaminants with it). You could repeat this process depending on how much stuff comes out, but I only did it once. I will likely drain it again this winter.

I wasn't in a rush, so I actually left the drain plugs out for several days. Per the other thread, I refilled with Royal Purple (yellow metal friendly). My transmission and transfer case have been working very well... If not the same, they may actually work better with the Royal Purple (could just be my imagination) .

[rob love]

With regard to ATF, many manual transmissions actually changed over to that fluid over the years.

My only worries with the Royal Purple is it is a bit thinner, so more prone to leaking. But I can attest to the fact that on my (and many others) Dodge transmission, the improvement in shifting was quite noticeable.