Cold flow properties on M1 HM 10w40?

Joined
Jan 18, 2009
Messages
1,081
Location
oklahoma
I was thinking of switching the HM 5.9L magnum engine to 10w40 instead of 10w30 because it has been getting well over 100* here consistently & I am under the impression that 10w30 is not good above 100*??? If that is the case, and I switched to 10w40 instead, will 10w40 M1 HM still flow okay approaching 0*???
 

JHZR2

Staff member
Joined
Dec 14, 2002
Messages
46,811
Location
New Jersey
10w-40 will have roughly the same cold flow characteristics as 10w-30. In cold conditions, youre testing on the 10w- portion of the specified viscosity. The 40wt will be a bit heavier than the 30wt, but the question becomes necessity. Being over 100 consistently isnt an issue as much as use, HD use, trailering, high load, etc. is. UOA is the best way to decide if 40wt provides benefits. if youre doing a lot of heavy use, you can postulate that likely you will see benefit from a 30wt oil, and go for it. the practical difference between the two at 0F will be nil.
 
Joined
Sep 23, 2006
Messages
11,268
Location
Bad Axe, MI
 Originally Posted By: FastSUV
I am under the impression that 10w30 is not good above 100*???
That's wrong, M1 10-30HM will do fine in them temps(well built oil),i have that in my '99 Z71 5.7 right now,have seen 90's with heavy towing (4-8,000 lbs) never an issue for me and my truck,oil pressure always around 40 psi,coolant around 210 Use it with confidence.
 

FastSUV

Thread starter
Joined
Jan 18, 2009
Messages
1,081
Location
oklahoma
okay guys, well that is why i am asking. With all the hoopla about HDEO's lately & the old "thing" about using a thicker oil in an older motor, I was wondering if I needed 10w40. For example, in my old 305 '92 Camaro I ran Castrol GTX 10w30 until 160k and then as it got older, I switched it to Castrol 10w40 HM. On the 5.9L V8, I have 180k and it was switched to M1 HM from regular M1 silver cap at about 150k...but still 10w30. I do tow a light trailer every now & then and it has larger tires and high miles so I was wondering if this was a good candidate for the thicker oil? SOunds like since th motor is in good shape (due to years of loving car with Mobil-1 oil LOL), that there would not be much benefit of switching to 10w40. The heat was the main reason I began thinking of this because many of the oil charts in owner's manuals suggest 10w30 is good to 100*F and that is all.
 
Joined
Dec 26, 2006
Messages
1,648
Location
Little Rock, AR
Regardless of what the spec sheet says about what temp it'll flow at - I wouldn't put M1 10wXX HM in my vehicles over the winter. Put a qt in your freezer over nite (mine is ~ -12degF) and see if you'd want that glob in your crankcase at anything near that temp. I tested M1 HM 10w30 - it was about like room temp honey. 5w30s (non-HM) slosh around just fine in this test. I would choose M1 HM 5w30.
 
Joined
Sep 23, 2006
Messages
11,268
Location
Bad Axe, MI
If that engine is in good condition good oil pressure no smoking/ticking/knocking etc you'll be fine with the 30w,i ran the HM 10-30(-54 PP) all last winter in mine no issues instant pressure,but thinking of testing 0w20 AFE in there this winter. i agree when the 5w30HM hits stores use that..a synthetic can handle the heat(100deg)
 
Joined
Dec 4, 2008
Messages
134
Location
Wi
 Originally Posted By: Nickdfresh
I'd go with the M1 10W-30 HM over the 10W-40...
DITTO
 

FastSUV

Thread starter
Joined
Jan 18, 2009
Messages
1,081
Location
oklahoma
well the motor is perfect...no smoke, good oil PSI. I have been using 10w30 M1 & M1 HM in it every winter since '01....I just don't like to switch weights and I'd never run 5w30 in it during summer so since this vehicle is retired as of 2008, & only sees enough miles for one OC per year, I just use the same weight oil year round.
 
Joined
Oct 18, 2007
Messages
3,756
Location
CA
I think you would be fine with either oil in the summer. Since you don't want to change but once a year, I would lean toward the 10w-30. How cold does it get there in the winter?
 

FastSUV

Thread starter
Joined
Jan 18, 2009
Messages
1,081
Location
oklahoma
 Originally Posted By: BuickGN
I think you would be fine with either oil in the summer. Since you don't want to change but once a year, I would lean toward the 10w-30. How cold does it get there in the winter?
20* is usually coldest it would be when the vehicle was started in the morning...but we have seen 0* many a time....
 
Joined
Dec 26, 2006
Messages
1,648
Location
Little Rock, AR
If you're doing one OCI/yr - here's what I'd do (and have done) - choose your favorite 10wXX HM oil (M1 would be my choice as well). Do the OC around March. Then, the following late November or December drop a pint or less of MMO or Neutra in the crankcase. Thus, you've still got your HM working for you, but you've now got better flow for the coldest months. And you've got a bit of year end cleaning going on. Good plan IMO.
 

FastSUV

Thread starter
Joined
Jan 18, 2009
Messages
1,081
Location
oklahoma
 Originally Posted By: ericthepig
If you're doing one OCI/yr - here's what I'd do (and have done) - choose your favorite 10wXX HM oil (M1 would be my choice as well). Do the OC around March. Then, the following late November or December drop a pint or less of MMO or Neutra in the crankcase. Thus, you've still got your HM working for you, but you've now got better flow for the coldest months. And you've got a bit of year end cleaning going on. Good plan IMO.
that is a pretty good idea...not sure if M1 would need that, but on a dino it may be good
 
Joined
Dec 26, 2006
Messages
1,648
Location
Little Rock, AR
 Originally Posted By: FastSUV
that is a pretty good idea...not sure if M1 would need that, but on a dino it may be good
I don't use it so much for cleaning - M1 HM shouldn't be leaving anything around to clean - but for me it's to have a little more peace of mind on those really cold mornings. Last winter I had Sch. 15w40 in my Sienna - but I topped off with a significant amount of MMO (much more than a pint - don't want to say) before the coldest part - so I slept good. (I don't know the cold visc. of MMO, but I did my freezer test on that stuff last year - it swished around like ice tea after a full nite in the deep freeze (much thinner sounding than my 0w20 M1 and 5w20 PP tests)).
 
Top