Ok... so just kinda asking for anyones thoughts on this. My Fieance drives a Kia Rio that was given to her by her father, who maintained it with Castrol 10W40 GTX for most of it's life with 2-3K mile changes. It's at about 110K if I recall. I've decided, with her driving routine (a few times a week into town and back, always warms up the engine) and relatively slow rate of racking up mileage, to switch over to a synthetic, and try to shoot for 1 year intervals, which will probably be around 5000-7000 miles. This will really simplify things because it's one of those vehicles that has to be jacked up or up on ramps to change oil in. (unlike my other 2 vehicles, which can easily be reached without it up in the air)... So for the sake of both saving some money and simplifying things, I think this is a good idea..
I asked her father about the 10W40... (which seemed odd, since most modern cars are calling for 30wt stuff).. he showed me the manual... which is very odd, in that it has one of those CHARTS that were common back in the "old days" (or on performance cars still today) with various oil weight recommendations for various ambient temperature ranges. What's interesting is that it recommends 5w30 for "low" temperatures, (like -20F - +40F) and then straight 30wt for 40F on up, then shows 10W-40 being compatible with a wide range of 0F - +120, then showing 20W50 for (IIRC) 60F and up, it even has a really low temp range spec for 5w20 (like -60F - 0) and some various oddball tight areas for straight 20 and 40wt.... Based on the chart, most people would logically deduce that 10W40 is the best all around oil for most situations... but we get temps below 0 fairly frequently, so personally, I think a 5w30 would be more appropriate.. And knowing what *we* bitogers know about the correlations between ambient temps and the operating temp of oil (that there is very little difference at operating temp), I see no reason why a 5w30 type oil, especially modern formulations, would not work year round in this vehicle. (especially considering the manual says it's *ok* to use straight 30wt for "hot" temps)... So basically... the whole chart looks like it was made up by a 9 year old just throwing out ideas with no basis in fact regarding the performance of modern oils (2002+). (Keeping in mind that I am trying to recall the chart from memory, the exact temp ranges I'm listing may not be 100% what the manual says, but the general idea is the same and the point)...
So anyways, I decided that before I switch it over to "full year" drains. I'll switch to synthetic, and do a 6 month or so interval on it. Looking down through the fill cap, the engine is not exactly clean, it's not terribly messy, but there are some deposits. So in case the synthetic somehow does manage to clean something, It'll get changed out sooner (doubtful, but "just in case"). I decided that with this possibility of any cleaning taking place, I'd start it's transition to synthetic through the summer and fall on some 5w40 HDEO Rotella Synthetic. I figure staying with the 40wt and introducing some heavy duty detergency will offer a buffer zone for the switch, no risk of working the oil too hard at all there.
So then the question is, when winter gears up again, I plan on switching it to 0w30 or 5w30 synthetic and leaving it for a year or so. Obviously the answer is "whatever I want to use" but I figured I'd ask if there is any reason to consider a particular oil over another for this type of extended interval in this engine(I think it's a 1.5L weedwacker engine). I'm considering gold GC or shell 0w30 synthetic delo, or maybe maxlife (so many people here love it), or maybe some Mobil 0w40, possibly Amsoil. Main emphasis on having proper cold flow in -20F mornings, but still be able to handle 90F summers without a problem for a year. I'm sortof concerned that since the engine has had a pretty happy life on 40wt, that if I switch to a 30wt it might be smart to lean towards the heavy side of a 30wt, or one of the "European" wide range 40wts like the 0w40 Mobil.
Any extended thoughts would be greatly appreciated!
I asked her father about the 10W40... (which seemed odd, since most modern cars are calling for 30wt stuff).. he showed me the manual... which is very odd, in that it has one of those CHARTS that were common back in the "old days" (or on performance cars still today) with various oil weight recommendations for various ambient temperature ranges. What's interesting is that it recommends 5w30 for "low" temperatures, (like -20F - +40F) and then straight 30wt for 40F on up, then shows 10W-40 being compatible with a wide range of 0F - +120, then showing 20W50 for (IIRC) 60F and up, it even has a really low temp range spec for 5w20 (like -60F - 0) and some various oddball tight areas for straight 20 and 40wt.... Based on the chart, most people would logically deduce that 10W40 is the best all around oil for most situations... but we get temps below 0 fairly frequently, so personally, I think a 5w30 would be more appropriate.. And knowing what *we* bitogers know about the correlations between ambient temps and the operating temp of oil (that there is very little difference at operating temp), I see no reason why a 5w30 type oil, especially modern formulations, would not work year round in this vehicle. (especially considering the manual says it's *ok* to use straight 30wt for "hot" temps)... So basically... the whole chart looks like it was made up by a 9 year old just throwing out ideas with no basis in fact regarding the performance of modern oils (2002+). (Keeping in mind that I am trying to recall the chart from memory, the exact temp ranges I'm listing may not be 100% what the manual says, but the general idea is the same and the point)...
So anyways, I decided that before I switch it over to "full year" drains. I'll switch to synthetic, and do a 6 month or so interval on it. Looking down through the fill cap, the engine is not exactly clean, it's not terribly messy, but there are some deposits. So in case the synthetic somehow does manage to clean something, It'll get changed out sooner (doubtful, but "just in case"). I decided that with this possibility of any cleaning taking place, I'd start it's transition to synthetic through the summer and fall on some 5w40 HDEO Rotella Synthetic. I figure staying with the 40wt and introducing some heavy duty detergency will offer a buffer zone for the switch, no risk of working the oil too hard at all there.
So then the question is, when winter gears up again, I plan on switching it to 0w30 or 5w30 synthetic and leaving it for a year or so. Obviously the answer is "whatever I want to use" but I figured I'd ask if there is any reason to consider a particular oil over another for this type of extended interval in this engine(I think it's a 1.5L weedwacker engine). I'm considering gold GC or shell 0w30 synthetic delo, or maybe maxlife (so many people here love it), or maybe some Mobil 0w40, possibly Amsoil. Main emphasis on having proper cold flow in -20F mornings, but still be able to handle 90F summers without a problem for a year. I'm sortof concerned that since the engine has had a pretty happy life on 40wt, that if I switch to a 30wt it might be smart to lean towards the heavy side of a 30wt, or one of the "European" wide range 40wts like the 0w40 Mobil.
Any extended thoughts would be greatly appreciated!
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