I posted a couple of days ago about the Rot. Synth. oil. Here is the answer from Shell.

Bob -

Thanks for the opportunity to respond to your inquiry, and thanks for using
Shell products.

Both ROTELLA T SAE 15W-40 and ROTELLA T Synthetic SAE 5W-40 are extended
rain capable.

The principal benefit of synthetics is their extreme temperature
performance. At subfreezing temperatures, they have better flow and
pumpability performance compared to mineral oils. This can benefit your
engine with better lubrication at subfreezing temperatures, and quicker
starts, which means less work for your starting system. At very high
temperatures, they can have better oxidation resistance. In most diesel
engines, oil temperatures don't get hot enough for this product feature to
provide a significant benefit.

Synthetic oils also offer the opportunity to improve fuel economy because
they usually have a lower viscosity grade compared to mineral oils. And
because they usually have lower volatility, synthetics can sometimes give
better oil economy - you may not have to top-off as often.

Recommending a drain interval for a specific engine is risky, without
knowing the current condition of the engine, how it has been maintained,
what duty cycle it operates in, what fuel economy it gets, how well the
engine is operated, and what engine life the owner expects.

A decision to extend oil drain interval should balance expected benefits
against risks that might accrue. The engine manufacturer recommends a drain
interval that in their experience provides optimum engine performance and
durability. To maintain warranty coverage, you should follow their
recommendation. Choosing a longer drain interval invariably involves some
compromise.

You may want to consider extending drain interval once your engine is beyond
warranty, especially if you operate in light duty service. But understand
risks you might incur. In the process of protecting your engine from
excessive wear and deposits, oil additives are consumed. At some point, no
matter what oil you use, oil will reach a condition where its performance is
compromised. Finding that point requires used oil analysis. To find the
optimum drain interval for your engine and your duty cycle, with the oil you
plan to use, I recommend used oil analysis as a tool.

Oil may also be contaminated in the crankcase. Fuel, coolant, and dirt are
all contaminants that compromise lubrication. The longer you leave oil in
the crankcase, the more risk of exposure to these contaminants. This is
another reason used oil analysis helps.

Here's a way to determine optimum drain. Switch to the oil you plan to use,
and operate for two oil changes at the interval you've been using. Sample
drain oils and have analyzed. If for both samples viscosity stays in grade,
TBN remains several numbers above three, contaminants aren't present, and
wear metals are acceptable, then extend drain interval by 25 percent. You
may keep increasing drain until one of the indicators shows distress, but
the longer you go the more risk you incur. Keep sampling and analyzing
drain oils, because normal engine wear and tear will cause increasing stress
for your oil.


Peter Van Benthuysen




Tel: +01 281 544 8253
Email: Peter.VanBenthuysen@shell.com
Internet: http://www.shell.com



> -----Original Message-----
> From: by way of Robb Capielo <robbc@rotella.com>
> [mailto:robert.gearhart@txelli.ang.af.mil]
> Sent: 02 December 2002 12:56
> To: Van Benthuysen, Peter PB OGUS
> Subject: Ask Shell: Rotella-T synthetic oil
>
>
> Peter,
>
> FYH.

 

Wow. An honest answer from a product representative. That's a new one!

 

What he failed to mention is filter systems and how they play in the big picture. I use dual-bypass systems and have had synthetic oils go 35,000 with the blessing of oil analysis labs. Oil does not break down only the additives that are in it do. The biggest detriment to engine life is dirt! Rememeber "YOU GET WHAT YOU PAY FOR!" If you always look for the cheapest then that's exactly what you will get! Put a bypass on it and keep the dirt out....they actually work, just a little spendy.

 

Thanks for your trouble, Bob. The facts sure can confuse one. I like to get under my car/truck at least 3-4 times a year; and changing the oil forces me to do it and take that "look around". I had a neighbor that used to buy a new car every 2 years. He never changed the oil but just added oil as needed.

 

How do you get your engine oil analyzed? How much does it usually cost? I change mine every 3000 miles. I'll probably keep that up but I would like to know how the oil condition is.