Oil Cooler and Engine Reliability
 

Hey all,
Has anyone gone through the trouble of performing an engine oil analysis before/after installing an oil cooler?

I recently installed a 35 row Z1 cooler. And let me just say that things aren't exactly what I expected (not knocking Z1's product). With the thermostatic plate it takes a good bit for the oil to reach temps... maybe 10-15 minutes. I am also concerned that the car might be starved of oil longer than it would be without the oil cooler when the car is being started up:

Maybe I'm being paranoid, but wouldn't the oil lines drain every time the engine is stopped, resulting in bubbles in the oil system, which in turn results in insufficient lubrication at engine startup (maybe only for a few seconds).

I'm worried that this would have a long term effect on the engine...

Can anybody chime in on this?

Why would the car be starved of oil?
Especially when in the second statement you're saying the car will have too much oil in the pan.
If the whatever you think is draining oil, you should be worried about the valves and the whole head not being lubed when you first start the car. (There's usually enough oil there from the previous day(s) to prevent any damage on startup)

And bubbles... What bubbles? Maybe 1? 2?
Bubbles aren't a catalyst for more bubbles. I suspect the camshaft slamming through the oil at 7500RPM is more of an issue, but obviously it's not that big of a problem, or you'd hear about motors dying every other day. If you grossly overfill your oil you'll have bubbling issues.


Real question, if the cooler mounted top up? Or top down?

Its mounted Top up. Thats how Z1 specifies to mount it.

The reason I suspect it could be a problem is the very same reason that you have to pre-fill a top up exchanger at install. Air in the oil cooler system has to pass through the engine before the engine sees lubrication at startup. If you were to not fill the heat exchanger at install, an entire liter-sized bubble would pass through your engine--which is why Z1 states that you HAVE to fill the core with oil at install.

If the hose is drained of oil, that 'bubble' (which is really the volume of the entire hose) would have to pass through the engine lubrication system before the engine (cams or crank) would see oil. This would just be a second or two, but I would think that it could create wear.

Anyway. Like I said, it could be paranoia... but I would love to see results of an oil analysis... especially if someone has already done one.

It's paranoia. My oil analysis has been fine every time. With as many people as we have here running oil coolers, if it caused problems we would have seen it by now.

Thats what I needed to hear... :D Thanks.

How about that thermostatic plate bit? I didn't think that with the thermostatic plate that it would take so much longer for the oil to heat up

It's going to take longer. That doesn't sound like its taking too long. If it takes too long to get up to temp in the cooler months, make a block off plate for the core. There's a DIY floating around here somewhere.

... Brother... You don't know why they say to do it then... And this is going to seem prickish, but I don't think you know how the system works either.

The engine has air in it. More air than oil.

You have to prefill the cooler because if you start it without filling it, you will effectively drain out 1+ quarts of oil out of your engine into the cooler, and you may cause the engine to STARVE itself. Not because of a bubble.




And it takes longer to warm up for 2 reasons:
1) The thermostatic plate is never closed, at "closed" or cold, it's circulating something like 20% of it's flow capability. Then it opens to 100% at 180 degrees
2) There is somewhere on the forum that says that the temperature gauge will read about 20 degrees cooler than it really is because the placement of the thermometer; it is right by the inlet (right out of your cooler)

yeah the Z for some reason has it's oil temp sensor located in the oil inlet instead of in the pan, I dunno why. It will read signifacntly cooler than those with an aftermarket guage in the pan. somebody with an aftermarket gauge want to post up the temp the ecu sees vs. the temp in the pan for us that would be great. sometimes there can be a very large difference between the 2 locations even without a cooler. and much more so when racing as the engine oil will be much hotter draining, and a greater percentag of heat will be lost in cooling. It's not uncommon for race cars to have +50 degree difference between inlet temp and pan temp

Whoa whoa. Don't say that I don't know how the engine works. The CRANKCASE has air in it, the oil passages should constantly be flowing oil! I think you are mistaken. If those passages are deprived of oil, lets say at 7000 rpm, for even a few seconds, you could seriously damage your engine.

In response to an empty oil cooler at startup: you are wrong. Make reference to Z1's install manual:

"Using Fresh Engine Oil, it is HIGHLY recommended that oil cooler core be filled
completely. This will prevent a dry start scenario and will help prime the oil
cooler FASTER!"

See how they say 'dry start'? That's what this thread is about. Yes the engine would be deprived of 1 quart of oil too. But that could potentially be fixed by topping off after the first start--the real concern is the dry start.

Your response seems prickish because it is. I wasn't saying that my engine was going to die today. I said it could damage the engine over time. Something like 90% of engine wear occurs at engine startup (at least on passenger cars), before engine oil has been given a chance to circulate and warm up. Imagine the volume of the empty oil passages within the block could cause the majority of the wear on your engine. Now imagine that you are adding the volume of two ~6 ft hoses to the volume of empty oil passages. I think its reasonable to be a little concerned.

I don't think that my original question warrants a "you don't know what you are talking about" response, brother.

Anyway. I didn't know that thermostatic plates still flow 20% below 180. Good to know. Thank you.

Well I would think the inlet temperature is what really matters since its what gets pushed into the block. Amirite?

IMO, I would prefer to know the temperature at the exit instead of the inlet. This will give a better reading at how hot the engine is actually running at without having a cooler affecting the reading.

I'm not saying Nissan did wrong by installing the sensor at the inlet, its not the point since its also a valid location.


When I blew the VVEL (oil starve) I think the gauge was saying about 280-285F after , now imagine how Hot it actually was !! no good hehe..

Ew. You are right. In the event of an overheat the safer number to go by should be the higher number... the outlet temperature.

Maybe the point of having it at the inlet would be more for gauging that the engine as it reaches operating temperature as it heats up--in that case you would want to go by the lower temperature number at the inlet.

I believe the thermostatic plate is at 10% open when cold. Not 20%. The reason why is not to mix cold oil with hot oil and shock it.

Ditto on simply blocking off the cooler when it's cool/cold outside. I simply used some blue painters tape. I was going to take it off today after the air temp hit 80° here in Houston yesterday, but the temps are plunging this upcoming week. Until daily temps start hitting the 90's, I may just leave half the tape on. Unless I'm doing a track day or aggressively driving back roads, oil temp hasn't been a problem.

Even with it blocked-off, and me aggressively paddle shifting last weekend on some back roads between Austin and Houston last weekend, my oil temp never went above 220° and quickly dropped down below 200° once we got back to a steady cruising speed.

I don't see how there is any reason to be concerned. All you are doing with an oil cooler is adding an additional oil flow loop to the system without interfering with the original system. To account for the increased capacity you have to add more oil, but the primary oil flow of the engine never changes.

The only time a dry start would occur is if you didn't prime the cooler, and it would only happen once before you added the additional oil. After that the whole system is full and operates as it does from the factory.

Also, if you are concerned with it taking longer for the oil to heat up try using a 0w40 which will flow better when cold.