5w-20 oil for the new Mustang? Educate me about oil!

[qcwang]

Wondered if someone could teach me the concepts behind use of these lighter weight oils.

In my Motor Trend magazine that featured the new Mustang, I noticed in the picture of the engine that the oil cap had 5w-20 as the recommended oil for the car.

I have noticed over the past few years Ford and Honda are using the lighter weight oils in their cars. Our Honda Odyssey has 5w-20 as the recommended oil.

I have read that there is some "CAFE" (corporate average fuel economy,or something like that)law/regulation that car companies are trying to meet. Using a lighter weight oil improves the milage just enough to meet these requirements.

I have also read that the machining of the engine now is so good that tolerances are tight enough to warrant a thin oil.

Is any of this true? Or other reasons involved?

I use 20w-50 in the P-car and it seems funny that there is no overlap between the oils compared to the van. One would think engine protection would be compromised with a thinner oil.

Thanks for your thoughts!

[RallyJon]

Subaru specifies 5W-30. Audi and many European mfrs specify 0W-40. Anyone who runs a WRX on the autobahn or significant track time runs 20W-50 or higher, or will spin a main bearing--guaranteed. Mfr recommendations are not for you and me, they are strictly for maximizing fuel efficiency while keeping the engine alive through the warrenty period, assuming an American housewife driving the whole time between idle and 2500 RPM at 1/3 throttle or less.

Look in the owners manual. Most specify an "extreme duty" weight. This is the weight enthusiasts should use.

[tchanson]

Originally posted by RallyJon
Look in the owners manual. Most specify an "extreme duty" weight. This is the weight enthusiasts should use.

Not Honda.

As noted above, they now specify strictly a 5W 20 on most of their new vehicles, with no other recommended options, regardless of operating conditions and/or ambient temps. Like Ford, they now thoughtfully stamp "5W 20" on the filler cap itself to reiterate the point.

That being said, I would think a 5W 30 Mobil 1 would be a logical alternative.

Tim

[UconnTim97]

I used 5w 30 in my Accord for 100k miles and had no problems at all.