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*???
If that is the case, and I switched to 10w40 instead, will 10w40 M1 HM still flow okay approaching 0*???