operating temperature question

[ramonesfreak]

car seems to be running a little hot suddenly

just drove car about 30 minutes, mostly highway driving at 65mph, some stop and go, nothing unusual, mostly 5th gear

weather was 76 degrees and 86% humidity

noticed my temp gauge right in the middle (to just slightly more than half-way) which seemed a bit hot to me.

my temp gauge is never that high. it usually sits between the first two white bars at the bottom of temp gauge

yesterday, i checked the oil and noticed a zero reading on dipstic. i added 2 quarts of 10w-30 mobile 1. now the oil reading is at the maximum fill mark on dipstic....more than usual for this car. i usually keep it right in the middle between the marks. oooops

about 1 year ago, i had oil hoses replaced by mechanic and had him change oil while hoses were off. neglected to ask him what weight oil he used, though i did request fully synthetic which is what i usually use...my point is i dont know if he used 5w-40 or 10w-30 or whatever

my question is, can slightly overfilling the oil and/or mixing oil weights effect the temperature of these engines?

just ordered a filter from PP and will be doing a fresh oil change asap regardless

[steely]

Right in the middle is supposed to be normal.
Here's a graphic I picked up here once - I regret that I cannot credit it to it's owner.

PS - mine runs closer to the ~190 mark.

[Steve@Rennsport]

If I can add to Dan's post,....

JMHO,.......Thermostats open between 180-185 degF and I like to see these engines run between 190 & 220 degF. The 220 mark is the tiny hash mark on the gauge face directly across from "Normal" on the graphic. 248 is too damned hot (paraphrasing my buddy Bruce Anderson) and not conducive to maximum engine longevity.

Modern synthetic oils function well above 275 degF, however the propensity for oil leaks rises exponentially when the engine operates in these high temperatures. For that reason alone, I like too maintain operating temps below 200 to maintain the integrity of all the gaskets, seals, and O-rings.

Performance really begins to fall off when oil temps rise above 210 degF so thats something to consider due to high cylinder head temps and reduced volumetric efficiency.

My advice to "ramonesfreak" would be to use a 15w-40 in hot weather and at those temperatures, leaving the lighter oils for water-cooled cars. Overfilled oil systems result in high oil temps so make sure you are making any dipstick decisions at operating temps (above 190 degF).