NOSLO6

Hi folks,

I have an 08 Z51 and this spring I switched to a Dewitt's radiator with an on-board oil cooler (part # A05AE). My hope was that it would help with the high oil temps I was seeing during track days with the small factory Z51 oil cooler.

I didn't make it to a track day this summer, but did a track day a few weeks ago in 50F temps and saw oil temps go above 260F about 10 minutes into the session, at which point I'd pit or do a few cool-down laps. This represents an improvement over the stock cooler, but was not the result I was hoping for given the cold air temps (we get 90s here in the summer).

My car is a cam-only LS3 with 3.90s and makes more power (and heat) than stock at < 500 rwhp, but is not a forced-induction or ridiculous-hp car. I inspected the rad and there is no damage to the fins and all was installed and burped properly. Coolant temps are fine on track.

This is not a race car and I chose the big rad over an external oil cooler at the advice of Dewitt's. It starts to be a pretty expensive cooling fix if I add an external oil cooler at this point.

What solutions would you consider?

VetteDrmr

Considering you've already modded the car internally, tuned, and gears, plumbing in an additional external oil cooler for $200 or so seems to be quite a worthwhile investment to keep your temps under control.

HTH, and have a good one,
Mike

Painrace

This hood helps a cooling lot and improves front down force but it is not cheap:



Jim

froggy47

I don't think 260 is too hot after 10 min. What temp do you want the oil to be at?

rustyguns

your not getting enough air through the radiator

SouthernSon

Added coolers and bigger radiator after temps were well over 300 and now I get close to 290 sometimes, but mostly 275 to 285. Add power mods and live with higher temps. I haven't seen a real detriment yet after >8k road course miles.

wallyman424

yeah i don't think you gave the system a fair chance by stopping at 260 degrees. You really need to give the system shot to get to steady state.

Next time dont back off and see what oil temps do. You really don't need to let off unless it gets around 300.

Bill Dearborn

In 90+ temps my Z06 runs around 260 and in cooler temps it stays about the same.

Bill

CHJ In Virginia

I agree with Wally - run the snot out of it and see where it stabilizes. 90 deg summer days will give a different final temp than will a cool fall day for sure. The computer doesnt start pulling timing till you get to over 300 deg oil and the stock M! formulation can handle that. Lower temps, I run 265-270 on a 100 deg ambient day - are much better for longevity.

sothpaw2

+1

265-270 oil is all that I see now in 100+ deg weather. An additional external cooler kit won't be too expensive--I found a nice used one on here for $300.

trackboss

the built in oil cooler dewitts uses is pretty small so don't expect a whole lot of cooling. In their defense there is only so much room in the tank. I wouldn't worry about temps until you start getting up to 300. My '99 has easily got up there on track when I had the dewitts and I don't rev the motor high at all. I've since completely redone the cooling system.

Gearhead Jim

FWIW, oil temp does not force the radiator fan to High until the oil gets to 302'F, and the Hot Oil warning comes on at 320'F.

Using 5W-30, most folks consider 280'F to be entirely acceptable. Many run up to 300'F and don't seem to have problems.

Good luck!

geerookie

What weight oil are you running? Too heavy of an oil can cause temps to go up. If your motor is only a cam change then stick with 5w30 oil.

drivinfast

08 0r 09 several months ago same issue except FI. he jacked the car up after trying many things.... he found something to do with the intake shroud blocking the flow. FWIW

Painrace

WOW! use 5W30 in a road race car at 260 degrees plus. I have never heard that recomendation before. I recommend 20W50 but what the hell do I know.

Jim

Z06trackman

I agree to running it hard and see what temp you get before doing anything.

I recently installed a DeWitts radiator and a big external Mocal cooler on my C5Z. I made this decision after reading a ton of posts here and speaking with several vendors. My conclusion was:
Internal cooler = 20F drop
Quality external cooler = 40 - 60F drop

One of the posts I found is from an ex-road race LS motor builder who said they told their customers to shut em down at 270 due to main bearing clearance increase. I know lots of people run hotter with no problem, but I figured if I was going to drop coin on cooling improvements I wanted a big improvement.

This only cost $350 more than an internal, but I did all the fabrication. This took a fair amount of extra time (8 hrs), but I enjoyed it. I got a 50F drop and I am pleased. At the advice of a vendors, I did not get a thermostat becuase of reliability and pressure drop reasons. I do not regret that either, and I drive mine in the winter. (will block it off)

For those reading this who are considering cooling improvements:

Don't attempt to remove or install the fan assembly from the top. Remove the sway bar and do it from the bottom. The difference is like night and day! (I removed from the top with difficulty, gave up trying to install from the top after bending a bunch of fins on my pristine new radiator and skinning most of my knuckles - it practically falls in from the bottom with the sway bar removed - amazing)

Advice for making Aeroquip hoses: do not even think of using a hacksaw unless you love frustration - I found it nearly impossible. Buy a cut-off wheel and it's a piece of cake. (I don't think a drill will turn fast enough - need air driven or dedicated electric tool)

MJM

I agree with you. I run Mobil 1 15w-50. It gives you decent viscosity at 300 where as 5w-30 has thinned out significantly at that temp.

Stock LS1 I used to get over 300 degree oil temps. After installing a DRM and Ron Davis combo radiator and oil cooler I run hard all session long and never break 300.

Matt

sothpaw2

+1 No thermostat; I wouldn't want the pressure drop. Styrofoam cover with a base made from cardboard with header wrap for contact surfaces seems great. For winter, I've been hoarding styrofoam and I might look at fabbing some more covers for the oil pan area to further trap the heat in during winter.

rustyguns

I USE 20W50 AND HIT 290 WHAT THE HECK DO I KNOW?

dfinke23

The cheapest thing to do is remove the weather stripping on the cowl. It sounds silly, but I did it this past weekend and had a 25*F reduction. I wouldn't recommend it as a permanent fix, but it confirmed that a vented hood will be my next step.