Oil Temp, What is normal or acceptable
 

Curious what is normal for oil temp. My engines are pretty much stock 502's, have crossovers and build very little water temp but can build oil temp in the 260-270 range if I run them hard. Is this excessive?

Not if this is for short periods like WOT. What is your oil temp at a steady fast cruise?

well... not sure i agree w/ that. certainly if i saw 270 once in a while i would think its surviveable but if you are saying that you can run cold water temps and oil temps that high without ever stabilizing at some temp then i would suggest that thats not good for the motor at all. i would think that you would want to shoot for at least 165 water temp and to be able to run the boat at hard as you want for as long as you want and have the oil temp stable at 240 or 250. if the oil temp never gets stable ( and the motor isn't blowing up) then your cooler is too small. but while i will certainly get some grief here for saying this, i maintain that runing excessively cold water temps is a bad idea across the board and has no upside at all unless you are running massive boost or racing compression ratios.

At a steady fast cruise 3000-3300 RPM 200-220, long idle in no wake it drops to 140-150, 4000-4500RPM puts it up around 240-250 WOT it creeps up from there. Water temps never go past 130. Was thinking about adding thermostat setup to the crossover but with the oil temps spiking like that im hesitant. I am running synthetic (Amsoil) so hopefully it will be ok. Read an old thread about 502's having lots of restrictions in the oil system but I dont want to start a project now that the season is started. This may sound dumb but where is the oil cooler on these, is it a big deal to change out maybe I need to do that.

on mine , which are year 2000 mpi's , it is vertical on the front of the motor next to the filter adapter and will have a big water line coming in and out of both ends and the oil lines from the adapter running into the sides. and for the record, with box stock hardware, i run 170 water, 230 to 245 oil at WOT for as long as it takes to get where ever i am going. with the stock tstat and cooler the water temps come right up and after a bit the oil temp gets to 200 and will move between the 230 and 245 as a function of load. i will correct myself in one thing tho, i said that that is with all stock hardware and plumbing which is true. however i did make some changes to make sure the engine compartment is well ventilated and exchanges air such that even at WOT it doesn't get much hotter that ambient. i can't tell you how much that alone increased the performance and stabilized the engine temps. i had a race car that one day for apparently no reason started running the oil temps at 300 ... from the day bef when they where perfect. long story short, it turned out to be the simple fact that we had lowered the front spoiler down an extra 1/2 inch and shut off the air flow under the car. that flow was using the pan itself as an oil cooler. took the extra 1/2 inch off and everything went back to normal... i think the same is true in a lot of boat engine compartments where there isn't enough air exchange to allow the heat soak to dissipate. thats what i fixed on mine with great results.

I think you will be fine with the oil you are using. Maybe this winter you could look to change some things to drop your oil temps above 4000 RPM.

On your engines it should be mounted at the rear above the bellhousing, just follow the lines from your oil filter adapter, one will go to it. It has 2 high pressure oil hoses and 2 water lines to it. You could also pull it, open the end caps and see if it has crust built up in there. If it does, a dip in CLR or muriatic acid will make a huge difference.

A good thing to do initially is validate the tune is correct. Lean or too much timing at elevated rpm will make the oil temps go up quick. As long as the tune is good, it is most likely a matter of bearing clearances are a little tight. Keep your coolant temps low as possible, keep the engine room cool, run syn oil and when you see 260-270 pull back.

engines are low hours, maybe 40-50, could be tight yet. havent checked the timing, carbs are prob a little rich cause my transom is getting sooty.

If you have an oil cooler a good rule of thumb is 25 to 40 degrees hotter than water temp. You need to get an actual reading off the oil pan to prevent chasing your tail. I had similar deal with diesel motor and finally laser temped the pan and led me to the sender, just like that. I have never seen a proper running motor that isn't full blown racer with oil over 230.
As far as amsoil handling the temps, it may do just fine, but the other components may not do as good, ie. head gaskets, intake gaskets, and so on. :drink:

I guarantee you that 8/10 people that run there equipment hard for extended WOT will get oil temps above 230 degrees.

Ill take your word for it. I just have not seen it. Mine hit way higher last weekend, but just crusing is way too high.

Cloud
My bad I read that wrong I guess he did say "Peaking at" But still seams high and my oil temp only reads to 260!
You doing anything tomorrow???
Mendota or what?

I would say 280 is the max temp you should run with good oil. However, above about 240, bearing wear is accelerated. If you have a decent size oil cooler and you are running cold water through the engine, the next thing I would check would be carb jetting. Running lean will make your oil temps rise fast.

Personally, my engine has an oil thermostat at 212. Theoretically, i'd like to be able to stay at 212, but it doesn't happen. On intermittant WOT runs, i'll run between 212-230. On a long wide open run, i've seen as high as 250 oil temps. I think it's due to not enough engine venting, and lack of oil cooler effeciency. I think if someone is getting above 260 on wot runs, you need to back off, and either let the engine breath better, or invest in better oil coolers. I know the cooler is my next purchase................

We can run steady 6000+ RPM and the oil temp never moves off 218 degrees. You just need a large enough oil cooler, a thermostat and adequate oil lines to keep the oil cool. We run a single KE 13 plate bell housing type oil cooler and -12 lines with about 775 HP. At some point, maybe 850+ HP?....you would have to go to twin bell housing oil coolers.

are youall mesuring it in the pan or after the cooler going back into the block?

At the oil filter/thermostat housing before returning oil to the to the block. We also have a 270 degree high oil temp sender in the pan that would trigger dash warning lights and an audio alarm.

some interesting input, I will have to do some looking into it this week. it seems to be rpm related, because it barely makes any temp at idle/slow speeds. maybe I will give Chief a call and see what they say, they are their motors. BTW can you pull the coolers off without making a huge mess, maybe they just need a good cleaning inside like someone above mentioned.

Oil Cooler Upgrade
 

Can anyone make a good suggestion on oil coolers, brand and sizing. Running a 454 with stroked 496 crank, cam, aluminum heads, and intake with 850 Deman carb.. runs a bit hotter than the mercruiser stock engine. Stock cooler now is 2" x 12"

I have a stock setup 496HO. I put my oil temp sender in the remote oil filter housing. If I understand how the oil flow works, the oil pump picks the oil up from the bottom of the pan and then through the filter, through the cooler, and finally back to the motor to the bearings. On WOT runs I will see 260-265 degrees. This is before the cooler but the oil is still reaching this temp. Is this call for concern or should I also look into a better cooler? I wouldn't think bone stock would be inadequate and there are a lot of these motors out there....

How much of a difference do you think it will be if you are reading off of the pan vs the remote filter? My temp is around 240 after a long 4k run and I have my sender in the pan. I have noticed my oil pressure is lower after it heats up that hot.