Petzuk sent me a PM about a recommendation he got for the 2003 Cobras from Amsoil to use their 10w30. I think that is not a good blanket recommendation, esp. for someone who lives in Connecticut, which can have very cold winters and temps in the single digits and sometimes below zero.
Why? Let us look at the viscosity specs:
A mineral oil 5w20 spec:
100 deg C: 8.6
40 deg C: 48
Cold crank vis: <3300 at -25 deg C
Amsoil 10w30:
100 deg C: 11.9
40 deg C: 69.8
Cold crank vis: <3444 at -20 deg C
So, Amsoil's recommendation has a 20 point spread in the 40 deg vis, and a higher Cold Crank at a HIGHER temp. So it will not flow as readily in cold conditions at even the mineral oil 5w20. The 10w30 does provide the higher temp vis protection I have cited as being a good thing, while the 5w20 is only adequate at best.
But my recommendation was, and remains, the Series 2000 0w30. It's specs:
100 deg C: 11.3
40 deg C: 57.3
Cold crank vis: <2993 at -30 deg C
The 0w30 provides nearly identical high temp performance as the 10w30. But look at the diff in the cold crank. It is much more fluid than the 10w30, at much Lower temperatures. Thge 0w30 provides both the high startup flow capability and the high temp protection.
Plus, Series 2000 is claimed to have a better additive package - that it should, since it costs much more than the 10w30 oil.
See why I think that the oil "expert" neither dug deep enough into Petsuk's needs, nor the capabilities of its oil, nor the stated requirements of the mfr.
You have to look out for yourself in this world, so thank God there is this Forum.
Still, if he only drives the car on summer's days, the 10w30 is a OK recommendation - but do you know that, Mr. Amsoil Oil Tech?
Why? Let us look at the viscosity specs:
A mineral oil 5w20 spec:
100 deg C: 8.6
40 deg C: 48
Cold crank vis: <3300 at -25 deg C
Amsoil 10w30:
100 deg C: 11.9
40 deg C: 69.8
Cold crank vis: <3444 at -20 deg C
So, Amsoil's recommendation has a 20 point spread in the 40 deg vis, and a higher Cold Crank at a HIGHER temp. So it will not flow as readily in cold conditions at even the mineral oil 5w20. The 10w30 does provide the higher temp vis protection I have cited as being a good thing, while the 5w20 is only adequate at best.
But my recommendation was, and remains, the Series 2000 0w30. It's specs:
100 deg C: 11.3
40 deg C: 57.3
Cold crank vis: <2993 at -30 deg C
The 0w30 provides nearly identical high temp performance as the 10w30. But look at the diff in the cold crank. It is much more fluid than the 10w30, at much Lower temperatures. Thge 0w30 provides both the high startup flow capability and the high temp protection.
Plus, Series 2000 is claimed to have a better additive package - that it should, since it costs much more than the 10w30 oil.
See why I think that the oil "expert" neither dug deep enough into Petsuk's needs, nor the capabilities of its oil, nor the stated requirements of the mfr.
You have to look out for yourself in this world, so thank God there is this Forum.
Still, if he only drives the car on summer's days, the 10w30 is a OK recommendation - but do you know that, Mr. Amsoil Oil Tech?
