shade tree welder
Silver Member
Finding an API CD service oil would likely be difficult since that specification
has not been supported since 1984, the current API Service for Diesel
engines are CI-4, CI-4 Plus and CJ-4.
For sub zero weather I would suggest you follow your manuals suggestion
and run a SAE 5W-30 CI/CJ service oil. They are out there. Shell, I know
make one as it is in my tractor now, it is what they deem a semi-synthetic.
Below freezing it suggests a 10W single grade oils which again are no longer
supported under the CI/CJ specifications so you are not going to find a single
grade 10W oil manufactured. I will explain more this later.
SAE 30W does not now or did not ever exist, I am assuming it is a typo and
you or your manual meant SAE 30 single grade oil.
Based on the information you provided. I would make the following recommendations.
All service grades should be CI or CJ.
0ｰF and below: SAE 5W-30
Between 0ｰF and 32ｰF: SAE 10W-30
Above 32ｰF: SAE 10W-30 or SAE 30
Finding a single grade SAE 30 CI or CJ will be very hard, although supported
by the specification I do not know of any one who produces that product.
Back in the early days of multi-grade engine oils the viscosity index improver
(VII), the additive that makes multi-grade oils work, was lacking in some
performance areas, mainly high shear stability. As a result, it was not
uncommon for SAE 10W and SAE 20W oils to be marketed, as they did not
contain any VII additive, they were shear stable and were still servicable for
engines at low ambient temperatures. Fast forward 30 years and we have
excellent shear stable VII on the market that will last 5, 10 and even 15K
miles between oils changes as a result the 10W and 20W markets and
support have diappeared but no one goes back and rewrites the old manuals.
