Need your thoughts on 5w-40 Motul

[Du_tch]

Hey guys My 17GT PP has about 23k mikes on the clock. Ive always used Motul 5w-30 and last week I changed my oil and used Motul 5w-40 now I feel like this oil is too thick for the coyote motor. My car feels sluggish and hesitates when I get on throttle. Car is full time E-85 24/7. Is 5w-40 too thick? Keep in mind I drive this car HARD high rpm (7,600) about twice a week.

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[Du_tch]

Hey guys My 17GT PP has about 23k mikes on the clock. Ive always used Motul 5w-30 and last week I changed my oil and used Motul 5w-40 now I feel like this oil is too thick for the coyote motor. My car feels sluggish and hesitates when I get on throttle. Car is full time E-85 24/7. Is 5w-40 too thick? Keep in mind I drive this car HARD high rpm (7,600) about twice a week.

Also, Tuned by the greatest @AED so I know its not a tune issue.

 

[CrashOverride]

Many supercharger companies reportedly recommend 5w-50, as well as the Boss Mustang. I'm in the same climate as you and when I switched to 0w-40 (Mobil) I didn't notice any change. I don't know if CA has "summer" or "winter" e85, but if we do, then that could be it. Our summer oxygenated fuels are so bad that Cobb tuning creates a special tune just for california. Your e85 tuner might not know about our boutique summer blend.

There are some fluid engineers on here that know way wore than me, but any loss in power due to increased pump demand would likely be extremely small. Is it possible the crankcase is overfilled? Windage might be more of a factor than anything else.

 

[GregO]

Motul is top tier in my opinion. With an oil as good as Motul why 40wt. for a motor designed to use 20wt. ?
I use 0w-20 and don’t lose sleep when Redlining it. She’s built to rev like a Super Bike on 20wt. oil.
Doesn’t oil wt. have an impact on how quickly the VCT reacts ?

 

[Du_tch]

Motul is top tier in my opinion. With an oil as good as Motul why 40wt. for a motor designed to use 20wt. ?
I use 0w-20 and don’t lose sleep when Redlining it. She’s built to rev like a Super Bike on 20wt. oil.
Doesn’t oil wt. have an impact on how quickly the VCT reacts ?

Good thought. Maybe the 40w is screwing with the vct. Not sure. Im gonna drain it and switch back to 30w

 

[Du_tch]

Many supercharger companies reportedly recommend 5w-50, as well as the Boss Mustang. I'm in the same climate as you and when I switched to 0w-40 (Mobil) I didn't notice any change. I don't know if CA has "summer" or "winter" e85, but if we do, then that could be it. Our summer oxygenated fuels are so bad that Cobb tuning creates a special tune just for california. Your e85 tuner might not know about our boutique summer blend.

There are some fluid engineers on here that know way wore than me, but any loss in power due to increased pump demand would likely be extremely small. Is it possible the crankcase is overfilled? Windage might be more of a factor than anything else.

Crankcase is not over filled thats for sure. I think im gonna switch back to a 30w motul

 

[Grayghostcoyote]

you realize it’s 5w right? The second number is the viscosity not the weight ……

 

[Grayghostcoyote]

… the weight of the oil isn’t 30 or 40…… 5 is the weight of the oil the first number is always the weight …. The second number is the viscosity

 

[K4fxd]

It's not the oil. Ford uses 5w-50 in coyotes.

You will get better high RPM protection with the 40 weight oil. That said the difference between 30 and 40 is not much.

Oil is rated backward. The cold number should be higher than the hot number since oil is thickest when cold. But we have what we have.

20 weight oil is for gas mileage and drag racing, where you want some protection but want to minimize drag. Chasing that last hundredth.

IMO it has no place in road racing or any time you will be at high RPM for longer than 10 seconds at a time.

 

[GregO]

… the weight of the oil isn’t 30 or 40…… 5 is the weight of the oil the first number is always the weight …. The second number is the viscosity

You speaking of multi grade or single grade motor oils ?
W in multi grade = Winter.
Motor oil slang words are “weight” ie; wt.
Not many go around saying 20 viscosity, 30 viscosity etc. historically it’s been referred to as 20 weight 30 weight etc. or 20wt. 30wt. etc. again dumbed down slang for easy speak.
Now multi grade on the other hand is 5 weight (wt.) with the following upper case (W) referring to (Winter) but again it’s slang and 5W-20, 5W-30, 5W-40 etc. gets the message across effectively with both numbers to the left and right of (W)(Winter) representing an oil viscosity grade or weight (wt.) in laymen terms.

 

[Paul McWhiskey]

The first number in a multi viscosity oil designation represents the oils flow characteristic at low temperature. The second number in the designation is the viscosity (or weight) of the oil. Therefore, a 5W40 engine oil is an engine oil with a viscosity rating of 40 (40 weight) with the flow characteristics at low temperatures of an oil with the viscosity rating of 5 95wieight). It means that it will flow like a 5-weight oil at low temperatures instead of a 40-weight oil at low temperature. This aids in startup pumpability to reduce wear since the oil can be pumped more rapidly throughout the engine. It can also reduce the load on the starter to a small degree since higher viscosity oil requires more energy to pump.

So 0W-20 and 5W-20 engine oils are 20 weight engine oils. Likewise, 0W-30, 5W30, and 10W-30 engine oils are all 30 weight oils and so on. Depending on where you live this may or may not be of importance to you. If you live in the Yukon the winter rating is very important, if you live in Pheonix, not so much.

 

[WildHorse]

Doesn’t oil wt. have an impact on how quickly the VCT reacts ?

No.

Another advantage is thicker oils dissipate heat a lot quicker.

 

[GregO]

No.

I must be thinking of the early primitive days of VVT.

Another advantage is thicker oils dissipate heat a lot quicker.

You sure about this ?

 

[WildHorse]

You sure about this ?

Yes. Gets to the operating temp quicker than thinner oils for sure.

 

[GregO]

Lighter grades of oil have higher heat transfer coefficients than heavier grades. Lighter grades will pick up more heat from the engine and reject more heat to the environment which results in lower bulk temperatures in the oil pan.

That’s my story and I’m sticking to it.

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