- Joined
- Apr 4, 2023
- Messages
- 176
Both these grades of Castrol Euro are readily available at Walmart (and at the same price), so I was curious as to the actual differences between the two.
I understand they both meet the minimum performance specs necessary to have the various Euro manufacturer's approvals, and that, with the minimum HTHS set by those approvals, there is often little functional difference between 30 and 40 grade Euro oil.
As far as approvals on the bottle, the differences are:
--SL (5W-30) vs SP (5W-40) API ratings, which I speculate are based on the API/EPA rules for rating 30 vs 40 grade oils and does not represent any real difference.
--The 5W-40 has A40 and RN ratings that the 5W-30 does not have, which I also speculate might be a reflection of simply a requirement of a 40 grade (rather than strictly performance requirement) needed for those approvals.
Walmart, who are generally known to consolidate their offerings, carries both grades at the same price, so I was wondering how different they really are. So:
--Are my speculations above valid that the Porche, Renault and API rating differences mostly reflect a 40-grade requirement for those approvals (even if a 30-grade had roughly all the same performance specs)?
--Any significant difference in HTHS between these two Castrol grades?
--Both will meet the stay-in-grade Euro spec, but is there any significant shear-stability increase in the narrower-range 5W-30?
--Any other significant difference that might cause one to choose one or the other off the shelf?
--Any idea why Walmart carries both?
Thanks!
I understand they both meet the minimum performance specs necessary to have the various Euro manufacturer's approvals, and that, with the minimum HTHS set by those approvals, there is often little functional difference between 30 and 40 grade Euro oil.
As far as approvals on the bottle, the differences are:
--SL (5W-30) vs SP (5W-40) API ratings, which I speculate are based on the API/EPA rules for rating 30 vs 40 grade oils and does not represent any real difference.
--The 5W-40 has A40 and RN ratings that the 5W-30 does not have, which I also speculate might be a reflection of simply a requirement of a 40 grade (rather than strictly performance requirement) needed for those approvals.
Walmart, who are generally known to consolidate their offerings, carries both grades at the same price, so I was wondering how different they really are. So:
--Are my speculations above valid that the Porche, Renault and API rating differences mostly reflect a 40-grade requirement for those approvals (even if a 30-grade had roughly all the same performance specs)?
--Any significant difference in HTHS between these two Castrol grades?
--Both will meet the stay-in-grade Euro spec, but is there any significant shear-stability increase in the narrower-range 5W-30?
--Any other significant difference that might cause one to choose one or the other off the shelf?
--Any idea why Walmart carries both?
Thanks!