348 Oil - 5w40 or 10w40???

The practical difference between a 10W-40 and a 5W-40 is completely irrelevent unless you are starting the car at an ambient temperature under 0dF (although some might say 5W comes into play at 20dF.) But basically the difference is so small that you should consider them interchangible. At -30dF the 5W- has a modest benefit.

At the hot end of things, RedLines -40 weight oils are both rated up in the 4.6 cP range at 150dC (305dF) so, here again it is practically irrelevent the difference between the two.

 

+1

 

I used Mobil 1 10-40 until they didnt make it any more. They do have the mixture, but it has more additives for older engines than it used to. Now it's 10-30. In CDA we really don't need anything but 30W but in synthetics, 10-30 is what you get.

 

I use 10-40.I wondered if due to the cold weathere here that a synthetic 10-30 might be more engine friendly but I havent switched yet.

 

I use Valvoline VR1 Racing Oil 20W-50

A very reputable exotic shop suggested I use this saying it was the best oil to use for the 348. I tested it against 2 other oils and viscosity and VR1 came on top hands down.

Castrol Syntec was the worst



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Mario

 

I use Mobil 1 0w40 euro blend as it has higher zinc content than their other viscosity oils which should be better for the lifters. I wouldn't obsess over the base weight rating unless you drive in colder weather - look at the hot viscosity and additives. In terms of Mobil 1, the 0w40 euro blend should be best for our cars due to the zinc content for street use. For track, their 15w50 racing oil is probably better - depending on what your oil temp gets to. Not sure on other oil manufacturers, you'd have to look at them individually.

 

I've used the Agip SINT 2000 10W40 in 348s for years and still use it in our shop with good results.

Steve

 

If track use is in the mix, I can agree with higher viscosity. Oil temperature can be used to determine hw much added viscosity is desired.

 

Mobil 1 15w50

 

I use Redline 10W40

 

I use Shell elix ultra 5w40 in my 348, and it goes quite well, but I'm thinking about change to Castrol 10w60 that I use in my Hondas with very good results.

 

I drive my car the way she needs to be driven, hard..... and all other oils I tried, I was burning 1 1/2 to 2 L every 500 miles, Castrol was the worst. With the VR1, 1/2 a L per 1000 miles. And, my oil stays golden much longer, the others, 1500 miles and she was black.

But, each car is slightly different, you just need to find the right one for your car, climate and driving style.




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Mario

 

I used to use this before the recession. Now its Mobil 1.

 

That is not (quite) what I was refereing to. If you drive the snot out of the car and the oil stays below 265dF you should stay with xxW-40 weight oil. Only if the oil temps go above 285dF is xxW-50 weight oil advised. There is considerable discussion about temperatures in the 265-285 range as to whether xW-50 is needed, warented, mandated, or optional.

When I drive the living snot out of my F355 even in 103dF temperature on public back roads, I have trouble getting the oil over 265dF. At the track I have no trouble getting the temps over 285dF.

Oil selection is about oil temperature, and we have a guage that can tell use what oil to pick.

 

I must agree, Syntec in my humble opinion is garbage.

Mobile one has been and still is one of the best synthetics on the market. I have no experience with Vr1 though. There are better oils for racing but they are not practical for everyday use. Castrol R comes to mind but needs to be changed often as it can get build ups of acids and other harmfull chemicals.

 

Don't know about the 355 but on the 348, the max temp is 280 on the gauge. I think if I hit 285 that I would probably get a slow down light way before....not sure what the threshold is on the 348.

My 348 gets 20w50...period.....I don't even care what other 348's use.....I was only saying what I was using and not asking suggestions....Sorry if it seemed that way.



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Mario