I used to do regular oil at 3k. Lately I've been doing the Castrol Syntec blend every 5k and was starting to wonder if that was too long. I've heard that fully synthetic is thinner and is more prone to leaking...I guess I figured that with the blend you might get the best of both worlds.

 

i run 4 qts mobil 1 10-30 with 1 qt lucas. and change every 4-5k and when i change it, its still not completely broken down and my oil pressure is still great, even as late as 5500 miles

 

I used to run Mobil 1 10k. Switched to Amsoil and now do once a year since I don't put no more than around 15k a year on my Ram. I used to run 20k on Amsoil in my Jeep. To me blend is just a snake oil to get a few more dollars out of your pocket.

 

Another question is how long does your filter last. I could be wrong but most oil filters are designed to last for less than 5k , if that long. Also, you should still lube the joints at 3k and rotate the tires at 8K. I'm not saying I follow that schedule percisely but I do change the oil and filter and lube around 3500 and rotate the tires every other oil change.
Also, if you are burning oil, that no substitue for changing the oil. The oil that is being burnt is the lighter hydrocarbons, leaving behind the heavier hydrocarbons and the heavier parts of the additive package. The lighter hydrocarbons help lube at startup and the heavier hydrocarbons turn to sludge. I'm not sure about the additive package but I know if you have topped up using a total of four quarts and then changed the oil at 5000, that oil is very different from having topped up with one quart in 5000 miles. I'm not sure if that makes sense or not but my point is burning the oil isn't the same as changing it.

 

That is not true, and bull****.

 

Amsoil's oil filter is designed for 1yr or 25k. When I ran Mobil 1 I used the Mobil 1 oil filter for the entire 10k.



The misconception of Full synthetic leaking is because it will clean out all the sludge and build up. Sometimes that sludge and build up is plugging a gasket leak.