Choice of oil viscosity

[SimonDk]

(Yes let's bring that up again, shall we??! )
..... Bear with me and a thought I haven't seen argued before:

I've seen the original spec call for 15w-50, which by many is considered quite a heavy oil (compared to more often used 10w-40 e.g). Some speculate that this is partly because of its "hot, Italian climate birth".... I call bollocks -- Aprilia surely will know and spec the bike for global varied climate use?

Now then: I read that some (most early?) bikes seem to run a cooler 65*C thermostat, while others are 75*C. I imagine, that this must have far greater significance for engine conditions/oil behaviour than atmospheric temp.?

Again, because none in hot climates have reported difficulty in keeping coolant temps low enough once on the open road, I conclude that the radiator performance is adequate, and engine won't sense ambient temperature.

I.e low coolant temp. bike, then 10w-40 is a safe (better?) choice... :o) And if choosing this, just as a precaution don't pin it straight off a hot town/standstill interval, where the oil will have thinned the most ( - some of course will flog any bike like a red headed stepson)....

[Aladinsaneuk]

oh my....


ok, i have asked a similar question based on geograhical location - ie, why does an outback aussie bike in an ambient temperature of 30+ use the same oil as is used in the frozen north - Doncaster?

apparently its down to tolerances :)

but re the weight

once andy has woken up from his nap, and had his pad changed, he will be along to post a technical update from aprilia that allows the use of 10/40 for clutch slip reasons....

more important, imho, is the choice of semi or full synth oil - in simple terms, pre 2001 semi, later bikes can use full - be warned that is not definite dates btw!

[snapdragon]

scuse me butting in having a non-falco - the specified oil for mine is 5w-40
recieved wisdom says - "well you're not in Alaska so use 10w40"


the recurring problem with these bikes is overheating
so
- if I understand the OP correctly (and that Is unlikely)
it would suggest that using the specified oil should negate that problem ?

btw I can find no 'motorcycle' oil for the weight, only 'car' oil

[Kwackerz]

I think youre right as whats the average running temp for the engine, about 77 degrees C? however I think coolant performance will have as much input as the thermostat choice when it comes down to behaviour of the oil. Coolant isnt necessarily standard across the Aprilia garage world and most definately isnt across the owner servicing world. one person's 50/50 is anothers 65/35 mix.. etc etc which will have a great effect on such a small cooling system.. also coolant brand and type will too.

[blinkey501]

(Yes let's bring that up again, shall we??! )
..... Bear with me and a thought I haven't seen argued before:

I've seen the original spec call for 15w-50, which by many is considered quite a heavy oil (compared to more often used 10w-40 e.g). Some speculate that this is partly because of its "hot, Italian climate birth".... I call bollocks -- Aprilia surely will know and spec the bike for global varied climate use?

I have used 10/40 and 15/50 on the falco, both were semi synthetic oils.
The temperature of the bike stays at 76 degrease unless the bike is stood.
There is no change of performance to the bikes that i have noticed.
Next time a service is due i will be using the cheaper oil of the two at that time has i am convinced it makes no difference.

[anzacinexile]

The ability of an oil to absorb heat has absolutely nothing to do with its viscosity.

The choice of viscosity is based on the running clearances and tolerances of the engine. Modern manufacturing techniques has resulted in the almost universal 20W-50 of the old days being now only used in corresponding engines from the 60's and 70's - my car for example runs 5W-15.

Bottom line is our motors can and do run quite happily with either weights but cooling properties do not come into the equation.