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15w40 vs 5w40

472 Views 5 Replies 6 Participants Last post by  pmat
just switched to the synthetic 5w40 rotella T6 from the conventional 15-w40 and what a difference it makes. Now that the weather is starting to cool down the 15w definitely increased crank time and the motor sounded awefull. Switching to 5w my truck is now "quarter turn to start" like normal and sounding nice and smooth. I really don't think the 15w is any good below 50F.

Don't like the price tag but I think I'm going to stick with the 5w year round. I'll keep and eye on the oil level and see if I can make up the difference by increasing the change duration.

How long are you guys running your 5w between changes? Only way to beak even here would be to do 6k/6 months. Is that too long? While I may not like the cost of synthetic, my motor seems to be loving it.
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I routinely go 6k on the 5w-40 with no issues. Did the same in the earlier trucks I had with 200k+ miles on them. Oil looks dirty but heck looks dirty after 2k.
On my daily drivers, I change every 3,000 miles (and rotate / balance tires). The trooper isn't driven much so I change it twice annually.
I have been running full synthetic for a few years now. I run 10k per change with a filter change at 5k. Most of the time, even at 10k, the oil that is coming out is not black. I run this interval on all my cars. The Rodeo is new in the driveway with a lifter tick, so it will just get regular oil with an additive for a few thousand miles before I put the synthetic in.
I run mine for 12,000Km with a filter ever 6000Km. When you change the filter you just need to add about a quart so it saves you some cash.
I run the 5w40, and change it every 3k. I got my truck from my father, and he never changed the oil, just added it as it burned it, so im just trying to clean some of the sludge out. Im gonna start running 5-6k intervals soon. My truck lets me know when its time to change it by ticking.
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