Wheelman

Back in the C4 days, I remember the z51 cars had an auxiliary oil cooler. I haven't seen much talk of that now, do the c6 z51s come with a similar option? Just wondering if an aux oil cooler would be worth adding for longevity. Want to keep my c6 for a long time

dougj1985

The Z51 model does comes with an oil cooler. Base model does not.

Gearhead Jim

Z51 cars were last made in 2009...

The stick shift Z51's had an oil cooler, I believe it was in the radiator for the first year or two and then it became a very small radiator in front of the main unit. AFAIK, the automatic Z51 C6's never had an oil cooler, our 2006 A6 and now 2009 A6 does not.

UncleRobb

My 2008 C6 A6 Z51 has a small engine oil cooler mounted in front of the A/C condenser.

drivinfast

my 06 stick Z51 has oil cooler in radiator driver side and trans in radiator passenger side

07MontyRed

My 2007 A6 Z51 does not have an external cooler ... wish it did (I remember the C4 days when Z51 included a number of things, like quicker steering, that it no longer does).

Tally Ho

You are correct. My 2006 A6 did have a power steering cooler but had to be removed to make room for the supercharger's intercooler.

Like dem Vettes

My 06 Z51 M6 has an oil cooler. On the hottest days in stop-and-go driving, the oil remains at a normal temperature.

RobLo

I have an '05 Z51 A4, I took out the Black Book and looked, according to the BB the Z51's (all Z51's, didn't specify Auto or Manual) came with "engine oil, transmission and power steering fluid coolers"...total cost of the Z51 package in 2005 was $1495.

Gearhead Jim

An export car, I presume? Or added by an owner?
You European guys get the good equipmenmt and the good roads.
It ain't fair.

UncleRobb

You are right, I have an export version (Euro). When has life ever been fair? Add the (partially) non-existing speed limit on the German autobahn and the Nurburgring Northloop nearbuy. On the other hand, cars and parts are somewhat more expensive here and I have to deal with oversea shipping.

Since we are talking about engine oil coolers in the Z51 version: I wonder if there is a thermostat and where it is located? The engine oil gets warm pretty quickly, so I suppose there is one.

Thanks, Robert

Gearhead Jim

My understanding is that the Z51 oil cooler (and also the similar-but-bigger Z06/GS air-oil coolers) do not have any thermostat. However, they are not a full flow system, the adapter by your oil filter "shaves" off a portion of the oil flow and directs it through the cooler. That prevents a problem in the cooler from killing your oil pressure.

I'm curious to know if the "shaving" feature near the filter might act somewhat as a thermostat? Would cold oil result in less flow through the cooler, then as the oil warms up more of it would get "shaved" into the cooler? Or not?

Even without a cooler, our 2006 takes a long time for the oil to reach 190'F (~90'C) which is what I like before using full throttle. The coolant warms up quickly, but the oil can take 10 miles even on a summer day.

UncleRobb

Jim, thanks for your explanation! I haven't thought about only part of the oil flow going through the cooler. Somehow the oil cooling system seems to act as if there was a thermostat involved since even in winter the oil gets warm quite quickly.

Here is a picture that I pulled up for my 2008 C6 Z51. Other model years might differ.



Here, however, it looks as if the pipe (3) to and from the oil cooler (1) is directly bolted to the side of the engine block. Still, there could be a (somewhat big) bypass either in the adapter in (3) or in the engine block.

I'm thinking of getting a (bigger) DeWitts radiator with built-in heat exchangers for engine (hot side) and transmission (cold side) oils. The plan is that if these heat exchangers are not sufficient (especiallly for track use in summer), to boost things up by putting (air) coolers into the flow path.

Gearhead Jim

I don't have any pictures, but others have said that the oil enters the pipe (#3) to the cooler (#1), through the piece marked #4 which fits onto the bottom of the engine, where the oil filter screws on.

Hopefully, some one will post photos for us.

I'm also assuming that the U.S. and European cooler setups are identical, which is probably true but not guaranteed.

Tally Ho

The BB says the same for 2006 but I know for a fact my 2006 Z51 optioned car (A6) does not have an external oil cooler.

orca1946

Now I need to go look at my 2006 Z 51 automatic to see!!!

UncleRobb

With the Z51 option, even if not the Euro version, for cooling the engine oil I would expect the car to either have an external (air) cooler or a heat exchanger integrated in the radiator.

I suppose you guys will tell us...

cadguymark

early Z51 had both Engine Oil & Trans Oil cooler built into radiator, later had external EO cooler

my Feb built 2007 is of the earlier design, by 2008 all had external

the advantage of external is that you can upgrade to Z06 cooler which is over twice as big, and in theory should do a better job of keeping temp down, but expect to pay $250 for a used one, a new one ain't cheap!

having said all that, the maximum temp mine has ever seen is 252 while driving hard laps, temp shouldn't really be a concern until you get to 280, when it hits 300, better think about shutting down or suffer possible consequences

in normal driving mine will sometimes get to 220-230 on hot days, spring or fall it is usually closer to 205

RobLo

Thanks for the good info, some numbers to go by...

bud miller

my 09 csc has oil, trans, and dif coolers.