A recent conversation with my father-in-law about motor oil sparked my interest in learning more about it. I have always used conventional motor oil with the mfgr's recommended oil viscosity (currently 5W-20 in my Ford Ranger) and changed close to recommended OCI (I will go about 4k in my truck). However, I'm considering switching to fully synthetic 5W-30 or 10W-30 (probably the latter, since I live in south Mississippi and temperatures seldom drop below freezing, and if then they normally won't drop below 20F) and an OCI (oil change interval) of about 10-15K (Castrol, for example, guarantees extended drain interval up to 15k with Castrol Edge) with a filter change every 5k.
However, I've been reading a lot about why some mfgrs recommend 5W-20 and I've read at almost every source I've visited that it's because of the CAFE (Corporate Average Fuel Economy). I've found sources (here (my favorite writeup thus far), here, here, and here to list a few). Basically, I've gathered that the gov't requires mfgrs to supply a sufficient amount of fuel-efficient vehicles to offset less fuel-efficient vehicles in order to maintain a certain CAFE overall in their fleet. By recommending 5w-20 oil, which I've read only increases fuel efficiency a minute percentage anywhere from .5% to 1%, mfgrs are able to increase the fuel efficiency on their overal fleet by a reasonable margin. The result, I've found, is that (with the exception of only one model that I've read about, and I can't recall which one) 5W-20 is not necessary unless driving in fairly cold climates (down to ≈-30F). In most cases, 5W-30 or 10W-30 are very safe. Also, I've actually read (this link, listed earlier, also hits this very thoroughly) that fully synthetic oil can be changed after 20k-30k (which I wouldn't consider regardless), but it is reasonable to consider an oil change of fully synthetic oil every 10k-15k, and 3k changes (even with conventional oil) are outdated and no longer necessary. However, many oil mfgrs still push it to sell more of their product.
Anyway, what do you use, how often do you change, and what are your thoughts?
However, I've been reading a lot about why some mfgrs recommend 5W-20 and I've read at almost every source I've visited that it's because of the CAFE (Corporate Average Fuel Economy). I've found sources (here (my favorite writeup thus far), here, here, and here to list a few). Basically, I've gathered that the gov't requires mfgrs to supply a sufficient amount of fuel-efficient vehicles to offset less fuel-efficient vehicles in order to maintain a certain CAFE overall in their fleet. By recommending 5w-20 oil, which I've read only increases fuel efficiency a minute percentage anywhere from .5% to 1%, mfgrs are able to increase the fuel efficiency on their overal fleet by a reasonable margin. The result, I've found, is that (with the exception of only one model that I've read about, and I can't recall which one) 5W-20 is not necessary unless driving in fairly cold climates (down to ≈-30F). In most cases, 5W-30 or 10W-30 are very safe. Also, I've actually read (this link, listed earlier, also hits this very thoroughly) that fully synthetic oil can be changed after 20k-30k (which I wouldn't consider regardless), but it is reasonable to consider an oil change of fully synthetic oil every 10k-15k, and 3k changes (even with conventional oil) are outdated and no longer necessary. However, many oil mfgrs still push it to sell more of their product.
Anyway, what do you use, how often do you change, and what are your thoughts?
