I tried 10W60 oil and it didn't do that well

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Short story long, I have a friend who have an Alfa 147 1,6TS, it is burning a lot of oil (he says something like 5L/10000Km, which is still under what Alfa considers "normal") when he uses 10W40 (I assume the cheapest oil the garage can put), so he decided to try 10W60, and we did the OC together this weekend.

Pros :

- car is running smooth, more silent
- doesn't smoke so blue/grey as it was with 10W40, in fact doesn't smoke anymore
- can now redlines without horrible metallic noise (did I said the car is usually a bit neglected?)

Cons :

- car is sluggish to rev (that was expectable)
- car is running HOT!

The last point is worrying me, normally it is constantly running at 90° (no oil temp gauge so only water temp), and fans goes on very rarely (traffic jam, long idling, etc). Now temp is constantly around 95/100°+, fan are almost always on, even on the highway at medium speed (110Kmh). When it idles, even for a short time, temp gauge goes almost in the "resd" zone (105/110°C)

I'm a bit surprised, can 2 grades make that much a difference? I know thicker oil = higher temp, but I mean this is an Alfa, supposedly ok with 10W60 in warm Italian climate, not the 18-20°Cish we have there!

Do you think it is a normal behavior? I've used 10W60 oil in the past, and my car (Mercedes 190E 1,8) didn't seem to see the difference.

Cheers
 
Probably compounded with the thicker oil cooling less and the rest of the car having some age to it, maybe the cooling system isn't performing like it was when new.

Then again some of these cars ran hot when new!
 
All things being equal, if you compare a 10W60 to a 10W40, the 10W40 will have a higher KV40, KV100, HTHS but the same CCS. It will contain substantially more VII polymer and less heavy base oil. As such, the 10W60 may be thicker but it will be MORE volatile than a 10W40, not less. As such it's not a smart choice if the problem you're addressing is oil consumption. A 15W40 or 20W50 would have been better options.
As regards running hotter, I'm not sure if this is right, but a 10W60 is thicker than the 10W40 across most of the temperature range that the engine typically operates. Your oil pump (assuming it doesn't leak) will drive the oil through the system at a constant volume. Two things...the pump will suck more power out of the engine to drive the pump to move the thicker oil and this extra energy is transferred to the oil as heat. The thicker oil will incur more frictional drag as it traverses the bearings and oil galleries and this frictional energy is also absorbed by the oil as heat.
My theory is that your engine is running hot because the thicker oil is running hotter. Yes, most of the engine cooling is done by the coolant system but part is done by the oil and it's the latter part that is suffering.
If the engine (except for oil loss) ran fine and redlined okay with a 10W40, then I would say try a 15W40. It will be far less volatile, and only incur marginally more pumping/frictional energy than the 10W40. Oh, and its HTHS will be higher so safer redline.
Good luck...
 
After owning two of those 16v TS cars, and participating on quite a lot of track day events, and experimenting with different oil grades I have to say my oil temperatures were never different what ever oil I used. Even on track with a car that has proper oil temp. gauge.
Only thing I've noticed is that after tracking Camshaft Variator would stay absolutely silent on idle whilst with 40 grade it would start to rattle.
 
there is something definitely wrong for any engine to get hot by using a thicker oil. I would try the 15w50 good luck.
 
Originally Posted By: 901Memphis
Probably compounded with the thicker oil cooling less


I'll bite, what's being cooled less, and how ?
 
Anybody venture to guess its bearing absolute clearance/specific clearance being on the high side ?
 
"it is burning a lot of oil (he says something like 5L/10000Km, which is still under what Alfa considers "normal") "

This means you never need to do an oil change as the oil is always replenished except just change the oil filter at the nominated interval top up and keep driving.
 
Last edited:
You could go back to the 10W-40 and see if the cooling issue is quieted.

Otherwise a radiator rebuild might be in your future.
 
I've had 2 alfa engines that consumed oil when I got them, but nowhere near what your friend's car does.

However, when I ran them on (then) Shell Helix Ultra 5w-40 for around 10k miles, and ran them hard when on temp (going through the whole rev range and at moderate to high loads the oil consumption completely stopped in case of the 16v, and halved in case of the 8v (higher mileage car).

if the car smokes blue under load, it's oil coming through the ring pack, and unsticking the rings could help. If the car smokes at idle, it's more likely valve stem seals.
 
Car ran "normal" with 10W40, except it smoked grey/blue at idle and under load (more grey smoke under light load), and did not redline correctly (scratching metallic sound at ~5000rpm+) (my friend is not very careful with its car, I know)

It has around 250000Km and is already shot, but it still drives fine in normal rev range, so my friend is willing to keep it till it dies, while doing only the necessary work if needed.

Also temps were fine two days ago, so I don't think there's something wrong with the cooling system (water pump has been replaced in april or may, along with the thermostat).

I'm surprised with the 10W60 temp, but for cost reasons this oil will remain in the sump, gradually replaced by 10W40 as long as it is consumed^^
 
Originally Posted By: Shannow
Originally Posted By: 901Memphis
Probably compounded with the thicker oil cooling less


I'll bite, what's being cooled less, and how ?



It's currently my understanding that the lighter viscosity oils are capable of greater heat dissipation due to density differences.
 
I would of thought the reverse more likely to be true. A liquid's specific heat is defined in terms of BTU/°F/lb. Your oil pump will be pushing a constant volume of oil through the engine but the denser oil will have a higher mass throughput. If you assume the amount of heat absorbed by the oil is roughly the same for both light and heavy oil, the denser oil will emerge from the engine at a lower temperature. Hence cooling should be better...
 
10w60's shear quickly. Its probably already a 50 grade and will likely be a 40 grade by the next oil change.

Coincidence and look elsewhere for the temperature rise.
 
How about you change rubbers on the valves? Oil will not solve issues. You cannot go indefinitely thicker with oil.
Also, for Alfa, try Selenia 10W40.
 
Originally Posted By: 901Memphis
It's currently my understanding that the lighter viscosity oils are capable of greater heat dissipation due to density differences.


Originally Posted By: Joe90_guy
I would of thought the reverse more likely to be true. A liquid's specific heat is defined in terms of BTU/°F/lb. Your oil pump will be pushing a constant volume of oil through the engine but the denser oil will have a higher mass throughput. If you assume the amount of heat absorbed by the oil is roughly the same for both light and heavy oil, the denser oil will emerge from the engine at a lower temperature. Hence cooling should be better...


Exactly correct, quart for quart there's really little to no difference in heat transfer capacity, the denser one slightly better thermal capacity.

There's a logical flaw that permeates BITOG, from 101 through many many discussions.

Most of the energy that the oil is "carrying away" is generated by the oil/mechanical interaction in piston/bearing areas, and not "carrying away" heat as the popular thought is.

Originally Posted By: bobbydavro
Thicker oils have more internal friction and will run hotter.


That's the point, and that's why the OEMs are going thinner and thinner, not to carry away heat, but to reduce the internal friction.

Here's where I switched from 5W20 synthetic to 20W60 dino in my Briggs Quantum mower.

It's air cooled, so all of the extra heat generated by running the thicker oil had to be dissipated by the machine reaching a new equilibrium point, that was only 10C hotter than the 5W20.

Not because the 20W60 "carried away less heat", but because it was generating more intenral friction...big difference.

Now with my thermocouple down the dipstick hole (L67 Caprice, water cooled), I've not been able to tell the difference between a 15W40 with an HTHS in the low 4s, versus an ILSAC 5W30 (HTHS 3.2)...the ILSAC could still hit 135C after 10 mins at 65MPH, 4,000RPM.
 
Originally Posted By: Joe90_guy
I would of thought the reverse more likely to be true. A liquid's specific heat is defined in terms of BTU/°F/lb. Your oil pump will be pushing a constant volume of oil through the engine but the denser oil will have a higher mass throughput. If you assume the amount of heat absorbed by the oil is roughly the same for both light and heavy oil, the denser oil will emerge from the engine at a lower temperature. Hence cooling should be better...




Heat transfer from engine oil sump to ambient is directly proportional to the temperature difference , no ?
confused.gif
 
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