4.6/5.4 3V V8s, variable cam timing, and 5W-20

[metroplex]

Does anyone know if 5W-20 ABSOLUTELY MUST be used with the 4.6/5.4 3V V8s due to the VCT technology? How sensitive is the engine to different oil weights (disregarding the manual and Ford's warranty just for 1 second)? The thickest oil I'm thinking about using in the 4.6 3V is 5W-30 (Mobil 1) because all of my other Ford modular V8s use 5W-30 synthetic and I would conserve logistical resources by stocking 1 type and weight of engine oil. Luckily all 3 Modular V8 engines use the same FL-820-S filter!

 

[gtss]

Disregarding the warranty and the manual for 1 second, the reasoning that I heard for why the switch to 5w20.
By switching nearly the entire vehicle line to 5w20 actually lowered Ford's Corporate Average Fuel Economy (CAFE) rating, and the model year that they switched, there were many carry over engines, with no changes to internal design or clearances. If this is all true, I personally can see no harm done in running 5W30
I live in Canada, have many mustangs including an 06 GT, and I know that the oil at -30 degrees is plenty thick and still lubricates reasonably well
gtss

 

[metroplex]

I checked with the Hemi owners (I know, it's blasphemous on :SNSign: ) and they said 10W-30 would set off a DTC and cause problems with the MDS. I'm not sure if using 5W-30 would have that same effect on the VCT for the 4.6 3V V8 though.

 

[anthony05gt]

I ran the 5-30 for 5k miles last year with no problems. I switched back to the 5-20 recently only because I found it in the store.

 

[LV51FER]

You can't even buy 5w20 in the UK. We use 5w-30

 

[MBDiagMan]

5W30 is fine unless you drive at the North Pole.

 

[JTGrant]

this is not much difference between some 5w20 and 5w30 on the vis scale.

 

[mustangsquared]

I "heard" that is was to increase fuel economy (being thinner so less drag on the crank and other internals) and that with the tight tolerences of the motor 30 or above would not lubercate as well.... of course once the motor breaks in I dont see an issue with 30 weight.

 

[Warlok]

UK

You can't even buy 5w20 in the UK. We use 5w-30

Are there many Mustangs in the UK?