Hi,

Can anyone tell me the reason why everyone recommends 20w50 without the reason being its in the manual for a 20v blacktop? What is the reason for such a high cold start viscosity? Why should I get that over lets say 0w40? I've read all sorts of recommendations such as 5w30, 10w40, 15w40, 20w60 and all sorts so I'm a little unsure which to get for my car.

Thanks.

Toyota FSM oil grade recommendations for the 20V blacktop...



Cheers... jondfee86

Another possible reason is that the viscosity of the oil affects the Oil Control Valve for the cam phasing.
Typically the clearances in it dictate the viscosity.
Too thin and too much leakage and slow response.
Same with too thick an oil.

Hank

s24a wrote:Another possible reason is that the viscosity of the oil affects the Oil Control Valve for the cam phasing.
Typically the clearances in it dictate the viscosity.
Too thin and too much leakage and slow response.
Same with too thick an oil.

Hank

Is that why the cold viscosity is high? What happens when the oil warms up and has less viscosity? I guess I'm just looking for a reason for a high cold viscosity. I ask cause I was a little strapped for time and I had a jug of mobil 1 0w40 that I used on my blacktop. Did I just messed up?

40vpurpletop wrote: strapped for time and I had a jug of mobil 1 0w40 that I used on my blacktop. Did I just messed up?

You should be fine.......

Viscosity in multi=grade oils can be thought of as follows:
Take your 0W-40 for instance.

At room temperature (20ºC) the first number is the TRUE viscosity. Its a "0" weight oil.
However, the viscosity improvers in the oil cause it to act like the second number when under heat and pressure. (a 40 weight oil)

So in the case above, you have a very thin oil that can act as a heavier oil in places that have pressure points , like bearings.

As to OST's comment that you will be fine, you will have to see how your engine's OCV performs with this oil.
You definitely will NOT ruin anything, but you might feel some difference in the action.
Also, it may be possible that your seals in the engine will be more prone to weep leakage with a thin oil (speak from experience here!).

Hank

20v's also seem to be known to consume oil. One of my speculations is that the 20v arrangement causes more valve stem wear, I had to have my bushings replaced on my rebuild. There's also the warning to not use the OEM style oil cooler as the 20v needs higher oil pressure to run properly.
So I don't think its the end of the world running the light oil, but I would change it at earliest convenience.
If I can find it, I want to run thicker oil eventually, but I'm still in break in period.