Do I put 10w-40 oil in my Gt-40?

[jackkloepfer]

10w-40 is what I thought I needed, but the manual says 40w40 for running above 50 degrees. I'm honestly not even sure what 40w40 is.

[MHayes]

RE: Do I put 10w-40 oil in my Gt-40?

40w40 is just 40w monograde oil. We've always used Castrol HD 40 in our GT40, which is supposed to provide maximum wear protection in warm climates.

[jackkloepfer]

RE: Do I put 10w-40 oil in my Gt-40?

Ive got some Mobil Clean 5000 10w-40. that should do the trick, correct?

[jackkloepfer]

RE: Do I put 10w-40 oil in my Gt-40?

anyone?

[M3Fan]

Re: RE: Do I put 10w-40 oil in my Gt-40?

Ive got some Mobil Clean 5000 10w-40. that should do the trick, correct?

Probably not. Do a search for "flat tappet cam" or "zinc" or "zddp" and you'll find your answers.

[jackkloepfer]

RE: Re: RE: Do I put 10w-40 oil in my Gt-40?

crap, if I use it just for this change, and use the right stuff the next time, do I run a risk of damage?

[mf01]

RE: Re: RE: Do I put 10w-40 oil in my Gt-40?

Any oil thread will have at least 5 different opinions on what to use. Make sure it has a good amount of ZDDP 1200ppm or above.

I personally use Shell Rotella 15w40. It has a little over 1200ppm of ZDDP, the same as many other oils used on here.

[steve-o]

RE: Re: RE: Do I put 10w-40 oil in my Gt-40?

10w-40 is a 10w oil that has the same viscosity of a 40 weight oil once at operating temperature. The oil is much thinner than 40w when it is cold, but once it warms up it will not thin more than a 40w at the same temperature.

Hope that helps you make your decision.

[DanielC]

RE: Re: RE: Do I put 10w-40 oil in my Gt-40?

Short answer, no.
I use Valvoline VR-1 racing motor oil, Motorcraft FL1-A oil filter. I have 2139.2 hours on my engine. Do not use orange oil filters.
The GT-40 engine is a flat tappet cam motor. It needs the ZDDP additive for long camshaft and lifter life.
Most modern oils are designed for roller camshaft motors, that do not need this additive. They can hurt your motor.
My understanding about multi viscosity oils is that they are only checked at two temperatures. Away from these two temperatures, and the viscosity is not the same as a 40 weight oil hot, or a 10w oil cold.
Use a straight weight oil, and warm your engine up before you "get on it.":

[skijones]

RE: Re: RE: Do I put 10w-40 oil in my Gt-40?

Would a 5.8 HO in a 99 be a flat tappet motor?

[Hollywood]

RE: Re: RE: Do I put 10w-40 oil in my Gt-40?

All PCM factory Ford marine engines are flat tappet

[steve-o]

Re: RE: Re: RE: Do I put 10w-40 oil in my Gt-40?

Short answer, no.
I use Valvoline VR-1 racing motor oil, Motorcraft FL1-A oil filter. I have 2139.2 hours on my engine. Do not use orange oil filters.
The GT-40 engine is a flat tappet cam motor. It needs the ZDDP additive for long camshaft and lifter life.
Most modern oils are designed for roller camshaft motors, that do not need this additive. They can hurt your motor.
My understanding about multi viscosity oils is that they are only checked at two temperatures. Away from these two temperatures, and the viscosity is not the same as a 40 weight oil hot, or a 10w oil cold.
Use a straight weight oil, and warm your engine up before you "get on it.":

Just to further clarify, the oils are tested at both the fully coiled and fully uncoiled positions of the polymers. Anything between the uncoiled and coiled temperature could be a varying viscosity. Once the polymers are uncoiled, it is a 40 weight, no different than any other 40 weight above the uncoiled temperature.

And to reconfirm everyone else, you should use a straight weight oil.

[jackkloepfer]

RE: Re: RE: Re: RE: Do I put 10w-40 oil in my Gt-40?

Thanks, all.

[Hollywood]

RE: Re: RE: Re: RE: Do I put 10w-40 oil in my Gt-40?

And for those of us who go out barefooting (WOT all day) when it's in the 30s??? I use 20w50.

[mf01]

RE: Re: RE: Re: RE: Do I put 10w-40 oil in my Gt-40?

Out of curiosity, how much does outside air temp matter when the engine is warmed up? My lake doesn't get above 75 degrees in the summer, so it's always got cold water to cool the engine. My engine stays between 160 and 165 almost all the time.