My last oil change was less than 1,500 miles ago. I've been using Chevron Delo 15-40 LE (CJ). This time got Delo 15-40 SDE (CK) at Speedco in my Cummins ISL 400 powering my motorhome. With the SDE (CK) I find that once the oil is up to operating temperature my oil pressure is six to eight pounds lower than before at ~1,500 RPM. I consistently saw 48 - 50 psi before and now I see 42 - 44 psi. I can't understand it - 15-40 should mean it has the same viscosity under the same conditions, right?
Delo SDE
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Nothing to worry about. ~10psi per 1k RPM is more than enough for literally every engine ever built, and remember gauge psi is really a measure of restriction to flow. So, slightly lower psi at same RPM means the oil is moving more easily through the passageways, which is a good thing. Lower PSI means there’s also less stress on the oil pump and shaft.
Originally Posted By: SubieRubyRoo
Nothing to worry about. ~10psi per 1k RPM is more than enough for literally every engine ever built, and remember gauge psi is really a measure of restriction to flow. So, slightly lower psi at same RPM means the oil is moving more easily through the passageways, which is a good thing. Lower PSI means there’s also less stress on the oil pump and shaft.
Are you saying the SDE (CK) has less resistance to flow even though it's 15-40, just like the Delo LE was?
Nothing to worry about. ~10psi per 1k RPM is more than enough for literally every engine ever built, and remember gauge psi is really a measure of restriction to flow. So, slightly lower psi at same RPM means the oil is moving more easily through the passageways, which is a good thing. Lower PSI means there’s also less stress on the oil pump and shaft.
Are you saying the SDE (CK) has less resistance to flow even though it's 15-40, just like the Delo LE was?
Search member “Caterham”. He has a great many posts relating HTHS and oil pressure. PSIG just measures resistance to flow; What I’m saying is it sure sounds like the SDE has (at least slightly) lower HTHS, which is showing up on the pressure gauge, it’s NOT saying there’s anything wrong with the oil or engine.
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