Can Mobile 1 FS 5W-40 oil be used in LS1 engines?

 

I have used it. Worked fine.

 

Why?

 

Based on a 2000 service manual GM specification 4718M was recommended for North America.
Mobil 1 has the FS 5w-40 on their site and that spec is not mentioned.
The same service manual says API SJ is acceptable for vehicles other than North America and the Mobil 1 page does list API SJ as one of the specs that oil meets.

If you really want to get into the weeds, figure out what superseded GM 4718M and what superseded that until you get to something current.

If you want to keep it simple, go to Mobil 1's website and use their tool. FS 5w-40 doesn't come up for a C5.

 

What does the "FS" stand for???

 

Full synthetic

 

Thank you. With most everything being full synthetic in the LS community, I never would've given it a thought, because that's all I use.

 

Yes, it will be just fine. Pretty much the same oil as Mobil 1 FS 0W-40 which has been popular around here for quite a while as well.

It's probably worth noting they also have a "FS" 5w30 now too, which would be a good choice too I think.

 

Why do you think Mobil 1 doesn't recommend it?

 

Probably because GM spec'd 5w30 for these engines and their online tool is basing it's recommendation off of that

 

They do recommend a different 0w40 but not the 5w40 in question.
Seems like if that oil were recommended for the C5 it would be on the list. And maybe they do for a different year or model, I didn't check them all.


I guess for the OP the question boils down to do you trust the recommendations of random people on the internet who have no vested interest in providing you accurate information or do you trust Big Oil with a team of professionals working to provide accurate information?

 

Ive been using M1 0w-40 since before it was available in the 5qt containers, back in 2005. It's good stuff. Just slightly thicker than 5w-30 cold, but better hi temp viscosity and protection. It's all I use in my LS7....

 

FS stands for the european designation Full SAPS (sulfates ash & phosphorous)
Think ZDDP, ( zinc & phosphorous) in the older US designation.
SAPS are classified as full, medium,& low. (FS,MS,LS)
Higher SAPS provides better engine protection, Lower Saps
provides better emission system protection for newer more sensitive catalytic
systems.

 

Short answer is yes.
I use the Euro spec 0w40 in my car

 

The 15W40 has this and that is why I use it in my flat tappet car.

But if you have Roller Tappets you have no need for it and it will damage a converter or 02 sensors long term.

 

Yup, The EPA forced the Automotive OEM's to warranty converters for 100k miles. So the Auto OEM's forced the oil MFG's to make the oil base stocks we have now = No or little ZDDP in the engine oils we are offered today. Now we have low tension rings and roller cam tappets in modern engines. Its all related, rings, cams and oils. This is a real problem with breaking in an older flat tappet can on an engine with high spring pressures. We've been removing the inner valve springs breaking in the cam with just the outer spring and obviously add high zinc oils/additives, but removing the inner spring is extra insurance. Flat tappet cams are not flat, they are ground with a taper on the lobe so that the lobe actually spin the lifter in the bore as the tappet rides up the ramp of the cam lobe. The lifter also has a crown to aid in the spinning. This spinning and sliding action is the "Breaking in of the cam". If the lifter does not spin as it rides up and down the new lobe = lobe is ground away by the lifter, sending metal throughout your new engine as it wipes out the lobe.
Roller cams do not need ZDDP as an additive Because the lifter is not spinning across the face of the lobe. The lobe is ground flat and the roller tappet rather easily rolls up and down the cam lobe.
If you want geek out about flat tappet cam wear, this guys explains it very well:

 

As good of an explanation as I've ever read. Nice, informative post. My only addition would be the tapered lobes also help keep the cam from walking forward, which is why no cam retainer plate is used on the flat tappet SBC.....