zeroptzero

I see Honda suggests that you can run 5w-40 oil if exterior temps go well below freezing (celsius). My thinking is that 5w-40 would be a good oil to provide extra protection, that viscosity satisfies some pretty stringent oil ratings that the typical 10w-30 doesn't even meet. My car has just shy of 60,000 miles, was thinking it might a good oil to change to and possibly keep the engine running like new even longer.

Is there anyone running the 5w-40 oil in their car right now ?, if so how does it seem to work ?. Is the engine any smoother, does it feel more sluggish, is fuel economy much worse ?, etc.....

Any real world opinions on this would be interesting, thanks very much.

phaphapho

I can tell you that although I just got my car, I am going to run a 5-30 synthetic in it. The engineers were obviously satisfied with the 30 when the engine is up to temp, but need the 5 when it gets too cold. The only reason for the recommendation that my research has uncovered for using 5w-40 in sub 0 (F) winter temps as opposed 5w-30 is to ensure that a synthetic is used since to my knowledge no 5-40 dinos are made. Many 5-30 dinos shear down quickly to something closer to a 5-20. My hypothesis is that if you use a 5-30 syn, you should be just fine for very cold temps.

I have used 5-40 in my Porsches but not in the S. Sorry I can't provide more help in that department.

dammitjim

This thread:

https://www.s2ki.com/forums/index.php?showt...&#entry17031294

will outline the kind of responses you can expect when starting a new thread about oil if you haven't searched or your username isn't Road Rage.

zeroptzero

well my answer to any complaint about newbie searches would be that I'm looking for real world experience on using 5w-40 on this vehicle. All the other threads are just arguments about whose favourite oil is better. It seems that very few people are running this oil visc. yet everyone has an opinion on it, it would be nice to hear some testimonials from owners.

I'll probably stick to running the 10-30 for a while until I hear some good recommendations from owners using the 5-40.

thanks for the replies.

iDomN8U

what testimonials do you want to hear? Nobody will be able to notice any difference between a 5w30, 10w30, 5w40 without some expensive equipment.

CST values at 100 C will give you a better idea what viscosity it will be at operating temperatures.

foxy_s2k

I use 5w40, as do most of the Greek members. Can't give you a comparison, as I don't know what it had before.

S1997

I am KW SC-ed and have been using Amsoil 5w-40 for over 40,000 miles. The car sees the track a lot. The engine never shows oil use and a weekend at the track does not produce more than a couple of inches of oil in the catch can. The only real difference I can actually see is that my oil pressure stays a bit higher on the gauge with the 5w-40 oil.

raymo19

And the folks at Amsoil recommend 5W40 for boosted cars. I suppose they would say use their 10W30 for NA.

jyeung528

i am na and i have used amsoil 10w30 and 5w40.

there is no way i can tell any differences...no way.

zeroptzero

so you find fuel economy and engine response to be similar between the two oils ?, no difference in oil consumption either ?. If that's the case I may look at running Amsoil 5w-40 permanently, I like the specs on that oil. thanks for the info and to everyone who has replied thus far.