Synthetic vs Petroleum

[Rawlco]

It is a myth that using synthetics will cause leakage on older engines. Synthetics will NOT damage seals or rubber components.

The one exception to this is: IF you have a bad seal that has been clogged with crud or a snake oil sealer of some kind the synthetic oil MAY clean out the crud or dislodge the snake oil causing an already leaky engine to leak. This is a very big IF.

[gregkar]

I'm a firm believer in synthetic oils, I use them regularly in all of our transmissions and differentials. they tend to withstand heat better and exhibit less viscosity breakdown. You can also go for longer periods between change intervals.

I'm just curious what everyone's thoughts are on using synthetics in the engines. I find it hard to justify that sort of expense, because engine oils are typically changed every 10,000 to 20,000 miles (depending on your fleet standards and truck application) Granted, you can get an extended enterval with the synthetic, but only an extra 10,000 miles maybe.

Do any of you think its worth the extra cost?

I use synthetics for trannies, differentials, and wheel ends on all 3 of my trucks (and trailers). So far, so good. The synthetic products seem like an idiot proof, no-brainer way to lower operating costs for the drive line components. I do NOT use them for the engines. I run a dump trucking and equipment transport fleet and as such, analysis shows even with synthetics that the oil gets contaminated far too soon to make extended change intervals a possibility. (Lab work by Caterpillar.) But I love the concept. If I had OTR trucks, I'd run it in the engines too.

Has anyone any thoughts on synthetic lithium grease? I was going to try that next....

[uncleal13]

My last oil change at Speedco I put in 100 percent synthetic Shell Rotella. I always use their oil analysis. I always changed regular oil 14 to 16,000 miles. But the owners manual says I can go 25,000 in light service conditions and 35,000 with the right oil. So I just had it changed out at 27,000 miles yesterday. The analysis showed excessive soot levels of 3.5, should be under 2.0 . I get this number with regular oil if I try to push it to 20,000. So I think unless you have extra filtration in place that extended drains are not a good idea.

[gregkar]

Excess soot....

Do you have a fairly modern engine under the hood? The older ones flatly won't burn cleanly enough for long change intervals. Also, vocational trucking builds soot. Also, excessive idling builds soot.

Now, considering soot is HIGHLY abrassive, you'd do well to change the oil often enough to avoid it.

The question to ask yourself now is "is there something I can do to lower the accumulation of soot?"

My last oil change at Speedco I put in 100 percent synthetic Shell Rotella. I always use their oil analysis. I always changed regular oil 14 to 16,000 miles. But the owners manual says I can go 25,000 in light service conditions and 35,000 with the right oil. So I just had it changed out at 27,000 miles yesterday. The analysis showed excessive soot levels of 3.5, should be under 2.0 . I get this number with regular oil if I try to push it to 20,000. So I think unless you have extra filtration in place that extended drains are not a good idea.