DGXR

I know that the oil life monitoring (OLM) system includes many different factors in calculating the oil change interval and turning on the "change oil" dash light. Lately there has been bad traffic and other conditions which cause my engine temp to spike. Everything is in great shape and the cooling system works fine. Yes the LT1 is designed to run hot and technically my car never overheats, but sometimes I forget to turn on the AC (and radiator fans) before it reaches 220F which is my comfort zone... it's been up to 228F several times in the past couple weeks. This is considered "normal" temps for the LT1 but relatively speaking, it's pretty hot.

I'm running Mobil 1 5w30. My question is, would you change the oil a little early because of the higher engine/oil temps? Or would you forget about the temp spikes, trust the OLM system and change oil when the light comes on?

Thanks

Crossed Flags Fan

not sure when you say to change a little earlier, when are you changing it now? At 3,000 or 6,000 miles? or by the OLM? or by months. How many miles are you putting on per year?
Personally I wouldn't go beyond 6,000 miles or 6 months.

John A. Marker

Start by cleaning out in front of the radiator any debris that has built up. When was the last time the coolant was changed and the system completely flushed? Fluid should be changed every three years or sooner. If you really want it to run cooler, replace the thermostat with a 160 degree and have the fans reprogrammed to come on earlier.

Change oil light is strictly a function of mileage. Your temps are well with "normal ranges". I would change based on the light.

antfarmer2

must pull the knock sensors to do a proper flush.

gungatim

if the cooling system works fine as you say, why would you have to manually turn on fans? doesn't the ECM/temp sensors/etc. work in that regard?

in terms of running hot and changing the oil sooner, if you are running mobil1 synthetic, it laughs at temps that low...it can handle temps that will be hot enough to warp the heads and blow the gaskets, so no, I wouldn't bother changing any sooner than normal. now the ATF is another story. I was taught in transmission class that if you hit over 230 on the fluid then it begins to burn and change to varnish, so I always change it on any vehicle that overheats for any reason. Granted that was 30 yrs. ago and new modern synthetics are probably better, but anything that can begin dissolving the clutch plates in any amount is never good IMO...

DGXR

Last year I did a proper cooling service: pulled the knock sensors and radiator drain, flushed it all including heater core, and filled with 50/50 green (it had green before). Also cleaned debris from the radiator and condenser, wasn't much there. And installed a galvanized wire mesh (1/4-inch grid) across the air intake above the black plastic deflector pieces to help keep out debris. There is no undue air restriction across the radiator. Cruising temp is 194-197F.

The service manual says change the oil at 7500 miles or 1 year, whichever comes first, so that's what I do. But I have never driven that many annual miles and the "change oil" light has never come on... so oil changes have been yearly at around 5000 miles.

Been driving it lots lately and will probably hit 7500 before a year. Plus, misc roadwork and issues/accidents have caused a lot of traffic in my area, so engine temps have climbed quickly and gone beyond my 220F comfort zone before I noticed. Again, no issues with drivability or anything else, just the digital gauge has me a bit concerned.

The additional annual miles AND the traffic conditions causing the temps to go higher (because I'm forgetting to hit AC) -- both factors are NEW and both are coming up during the same oil run.

Yes the temp sensors, ECM, fans, etc. all work fine. I guess the root of my question is that I am not comfortable with the engine above 220F. Lots of other owners worry about this and I hate to admit it but I do too. By the C4 LT1 book, even 230F is technically not overheating but in the automotive world, its pretty hot, and that's really my gripe... "normal" temps here are well above my mental comfort zone. Cooking everything in the engine bay is not fun so I avoid it where I can. I normally hit the AC anywhere above 220F engine temp.

Yes Mobil 1 is synthetic oil which handles temps better than conventional, but temps affect the oil life anyway.

Based on everyone's replies, it sounds like I am concerned about nothing.

I have the M6, cooking ATF into varnish is not a concern.

I have read many threads saying that, in addition to sheer mileage, the OLM also factors in oil temps, RPM/idle time, load/throttle position, number of cold starts, etc. You're saying the OLM does not consider any of these?

93Rubie

With routine street driving, I think your getting overly concerns with it.

Follow the owners maintenance schedule. Make sure YOUR driving fits the schedule you select and call it a day.

Even sitting in traffic your oil temps will NEVER touch those that I've seen while on a track with my LT1. I've come off the track after a 20 min. session and oil temps are north of 240. That is NOTHING to worry about with synthetics. IF they exceed 280 or so that is when changing it needs to be addressed.

230 isn't that hot. Most modern engines run in that range or a bit less sitting in traffic. Keep in mind the LT1 is reverse flow a bit hotter is nothing and is completely normal.

Mr. Peabody

Your vette is running as it was designed to.

I've put 100K on my own 95 changing oil every 7500 or one year and I always drive briskly and all too often in stop and go commuter traffic.

No need to be so concerned about your engine temps

DGXR

Awesome, thanks everyone for your replies. I'll just keep using the good oil and filters, and follow the recommended intervals.

P.S. 93Rubie, I saw your thread with several diagnostic videos. Thanks for taking the time and interest to make them and share the great info with everyone. Well done.

RollaMo-LT4

It uses more than just mileage, but they don't go into details.

From the '96 owners manual:
But as stated, the temps your seeing are perfectly normal and are not any cause for concern.

A cooling system in good condition, with the proper coolant mix and pressure, the boiling point is close to 260°F
In traffic, temps in the 215°F - 230°F range are normal and you car will idle like that all day without damage.

93Rubie

Glad you liked them. I have more in the planning stages, just need to shoot them. Finding the time is another matter.

1993C4LT1

Just saw the one on the opti test. That is badass

Kevova

Oil life is mostly effected by temperature extreme heat or cold. Type of driving and drivetime next. Overheating kills oil life quick. Oldsmobile spent a fair amount of time researching oil. During the early eighties Olds was trying to stretch out the oil change intervals to 7500 mi. It didn't really work the oil wasn't that good yet. Their studies yielded consistencies in how oil broke down. They learn by monitoring ECM data oil breakdown could be calculated. In the mid eighties a trip computer became an RPO and had a oil life function. Change Oil Lights or Messages started showing up on various models. Now the ecm can not determine oil quantity is assumes the correct oil is used, so it does not recalculate for conventional, non API or synthetic. Although GM pretty much had oil life figured out it wasn't until 2004 where it became the basis of schedule maintenance. In the late 80s there was a training video but no informational bulletin.

C5 4me

As I live close to you,I feel your pain & its not summer yet.But it sounds like your doing all you can to keep it running right.Last summer I had able chevy drop a 2core radiator in it just to be safe.I though my radiator wasn't bad till they pulled it out.It looked clean to my eyes,but looking at it uninstalled where the fans sit was full of crap inside the fins.