I have a 01 Corolla (with an 7AFE engine not the 1ZZFE) with 285k miles. It´s burning 1 qt of oil every 1300 miles which is acceptable for me. I can get a Synthetic 5w40 Oil almost at the same price of the Dino HDEO 15w40 oil that I´m currently using, the HDEO is API SL rated and I can get two main synthetics with the following ratings:
- PDV 5w40: API SM, ACEA A3/B3 04, MB 229.3, VW502/505, BMW Longlife Oil 01
- Venoco 5w40 & 10w30: API SN
My questions are:
Would I see any benefits using the Synthetic 5w40? My coldest starting ambient temp is 68 °F, so the 15w40 isn´t that thick at that temp.
Would the 5w40 increase the oil consumption? My guess is that the 5w40 would have a lower NOACK than the HDEO 15w40, I think the oil burning is being caused by the rings, valve seals are almost new and there aren´t any leaks. I don´t know how NOACK would affect oil consumption in this condition.
Would the 5w40 Synthetic harm my engine for being so thin? My car used Dino 20w50 98% of its life, this will be the first time in something that thin.
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According to this image a 15w40 has a 42% lower KV at 20 °C (68°F which my coldest temp). And PDS says that at 40 °C the KV of the 15w40 is 35% lower. That looks noticable for me.
What is funny to me is how USA people thinks that a 20w50 is a thick oil and according to that data in the image the viscosity of an 5w30 at 0°C-32°F is the same that the one from a 20w50 at 20°C-68°F that is our coldest starting temp. BTW is there a way to extrapolate KV of an oil knowing it viscosity at 40°C and 100°C and using the VI?
