420a Oil Cooler

09-18-2007, 03:52 PM
The 420a motor does not come with an oil cooler, it doesnt really need one in stock form but once it becomes heavily modified or a turbo is added, it is a nice investment. I have noticed that in the extremely hot weather my oil pressure has started to drop a couple psi. At idle it never dropped below 20psi before the turbo, now on a hot day it will sit around 10-12psi. Its not that bad with fresh oil but after 1500 miles or so it starts doing this.

This is just a guide to go by when installing an oil cooler, depending on the cooler you get will determine the fittings you need to buy. Here is a list of the parts I used.

- $50 True Flow oil cooler (11x5) 1/2 fittings
- $30 Sandwich adapter (3/4 x16mm) 3/8 fittings
- $25 6ft of 8-an SS hose
- $30 Two 8-an 90deg fittings
- $15 Two 8-an straight fittings
- $8 Two 3/8 to 8-an adapters
- $10 Two 1/2 to 8-an adapters
- $25 10-30w Synthetic oil (5.5qts)
- $5 New oil filter (Purolator Pure One L10193)
TOTAL: $198


*Note* - Its recommended that you use 8-an lines

1) Find a place to mount your oil cooler, I choose to mount mine behind the vent on the passenger side of the bumper. I had the most room here and also gave a short route to the oil filter. I had to remount some parts in that area to get the oil cooler up high enough where it wont get caught on anything. I had to make some brackets to mount the oil cooler.


2) Drain the oil from the oil pan and remove the oil filter, install your fittings onto the sandwich adapter. (Use teflon tape on the threads) Install the adapter where your old oil filter just was. (Put some oil on the o-ring to make it seal good) I put lock-tight on the adapter nut to keep it from coming off when I change oil filters in the future. The fitting point to the right side of the car.


3) Mount your oil cooler and measure your first line. Attach the fittings on it and install it on the car. Do the same for the second line. Go ahead and put your new oil filter now. Your oil filter is going to sit about lower now which will put it lower than the oil pan. I used the Purolator Pure One L10193 oil filter because its shorter and sits even with the oil just like before.


4) Make sure your oil lines arent going to get caught up in the belts and pulleys, or hit the tire when you turn. Go over all of your fittings once more to make sure you tightened all of them. Add about 5 qts of oil to your motor. Disconnect the coil pack and fuel pump and turn the motor over for a little while to pump the oil into the oil cooler. Check the oil level and add oil if needed. Crank the car and let it run for a few minutes. Shut it off and wait about 10min, check for leaks and the oil level to see if you need to add more. It took about 5 qts to fill my car up.




09-18-2007, 04:13 PM
Good write up.

What's the 'after' now? Have you noticed better operating temps now.

09-18-2007, 05:39 PM
I haven't even driven the car yet actually. I will update in a few days and let you guys know.

09-18-2007, 08:17 PM
Very nicely done... Added to the index...

10-01-2007, 01:58 PM
I haven't even driven the car yet actually. I will update in a few days and let you guys know.

Any update yet? Cooler running?

Is it true if you have cold winters these aren't good to have on the car?

10-01-2007, 02:12 PM

First thing I noticed was that the oil pressure dropped a little, seemed just a tad low at idle but about 10 psi lower driving around. Which is no big deal since I was still pushing 50psi. I have no way to see water temp or oil temp so dont have any proof of actually temperature drops but it does seem to help.
The only reason I could see someone saying they are bad for winter is because maybe it keeps the oil to cold. IMO the colder the better, the oil will heat up to a certain degree just cause of the motor heat so its not like the oil is going to be real thick. I wouldn't think it would be any different then before really. I have heard about a way to make the oil only flow through the the oil cooler when it reaches a certain temp. Not sure on this setup but have heard someone ran it on a 420a. Might want to look into that Dave.

I would still recommend this for all the highly modded 420a, its just more protection against your investment in an expensive motor. And its a pretty cheap mod.

10-01-2007, 02:48 PM
I have heard about a way to make the oil only flow through the the oil cooler when it reaches a certain temp. Not sure on this setup but have heard someone ran it on a 420a. Might want to look into that Dave.

I've heard of this too. It's almost like a thermostat piece that opens and closes based on temp. Seems to me though that then the engine would have too much oil in at a certain time unless when cold, the cooler held that amount in it. Can't remember where I've seen this though.

With the winter thing I've heard if it gets really cold, that the oil my be sludgy with it being farther away from the engine. The engine will heat up, so will the oil causing it to flow. But the outer reaches of the cooler and lines may be frozen, making it really hard to heat up and just cause a blockage. This is just what I've heard. I think the cooler is a great idea and would actually do it myself if I can get a positive answer about the cold thing. Even though I'm N/T, it couldn't hurt.

10-01-2007, 02:56 PM
There wouldn't be to much oil bc the oil cooler would hold the extra and it would circulate till the "thermostat" opened up. I can see were your going with the oil getting cold and not wanting to move. Using a 0-40w oil might help with that. It rarely gets below 30F here so im not worried.

10-01-2007, 03:00 PM
I live in Chicago. Very cold winters. We get excited when 30F is going to be our high in some months. I'm thinking as long as the engine is warmed up for a decent amount before the car is moved it should be ok. Just to get the oil flowing better and warmed up a little. I still may do it anyways.

10-01-2007, 03:21 PM
Im going to Chicago in month.

Yea I would think it would be fine. You could always just bypass the oil cooler if you start having problems and just use it in the summer.

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