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| [GMCnet] Synthetic oil Just some thought's [message #282221] |
Thu, 16 July 2015 01:11  |
BobDunahugh
Messages: 2465
Registered: October 2010
Location: Cedar Rapids, IA
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From: yenko108@hotmail.com
To: robmueller@iinet.net.au
Subject: RE: Synthetic oil
Date: Wed, 15 Jul 2015 23:27:39 -0500
I'm not saying here that any oil type is good, or bad. All engine
oils are the best they've ever been now days. And you need to match the oil to the service duty it's expected to handle. There are lots of angles to the
story of oils. What we have now is old tech engines in a new tech world. And
what's below should be considered fruit for thought. New tech products aren't
always the best for our old tech engines. All I ask is to think about what
you're doing. We need to do things that put us in our own comfort zone. Bob
Dunahugh
They say that syn's take heat better. That is correct. Gas engines have
been using mineral base oils for over 100 year. And now, oils are better than
they ever have been. And have performed well over all these years. If you had
gas engines operating at 300 degrees. OK. Synthetic oils would be the oil of choice. But our engines don't. We're in the 200 area. I just don't see syn oils as
fixing a problem that doesn't exist for us. I believe our old oils are good to
290 degrees. That's well above where we'll ever go. If we hit 250 degrees, our
engines are gone no matter the oil. I don't know syn oil limits. Let's say 1000
degrees. If that range was raised to 1500 degrees. Does that mean that it's
even better at 1500. Still doesn't make it any better for us when we operate in
the 220 range max.
SYN's can be used
for more miles. But that doesn't mean that the filter's life is extended. It's
really simple. The longer any oil is in use in any engine. The more the oil filter
gets restricted by contamination. And that means that the more oil is unfiltered due to the oil
filter bypass valve. By 3000 miles. I'll bet that our oil filter bypass valve
has alot more oil going thrue it then the filter. With our old
tech engines. They put alot of contaminants in the oil that the filter can't
take out. The oil, and filter needs to be changed at 3000 miles. I use diesel
oils in everything I have. SM rated oil is to be used in engines with SPARK
ignition systems only. CJ rated oils are for COMPRESSION ignition engines. (
Diesel ). Some oils are rated SM/CJ. These oils can be used in both. Diesel
oils are made to handle more heat, and contaminants then oils rated for spark ignition. ( gas ) SYN oils are great in
modern engines. As those engines are much cleaner do in part because of EPA
regulations. Thus contaminate the oil less. In our 08 Chevy Uplander. At 1000
miles. The oil is very clean at that mileage. At 1000 miles in the GMC. It's
black. And the best way to get that contamination out is to simply drain it.
Draining will get 99% of the contamination out of the crankcase. Not just what ever,
the filter may get. My daughter is a doctor. She can afford to get rid of her
98 Chevy Astro. She bought it new. She just loves that van. It's at 339,000
miles. Uses just under 1 qt for 3000 miles. I have a 96 Astro that's at
294,000. Same story. Can anyone say that syn oils could top that service. I've
seen 3 GMC's that have syn oils in them. And everyone of them have more oil
mist under them then my GMC with 154,000 miles. If you want a gas engine to
last. Change the oil ( whatever it is ) every 3000 miles to really get the junk
out.
I know there are people that build engines that recommend
syn oils. That's fine. I'm not saying they're wrong at all. And I don't know
the bases of what their recommendations are. Other than what I've mentioned
above. Just at lease change the filter every 3000 miles. But if you're going to
do that. Why not drain the rest of the contamination out will your under there
anyway. Oils cheep.Engines aren't. Most of the engines that I build are run
hotter, and harder than our GMC's. And the throttle is wide open most of
the time at extreme RPM's. That's alot more load than any GMC will ever see. As
for recommendations for oil. I don't have any. I just mention what's above. I'm more interested in the oil filter change. As for our old tech stock engines. I recommend
what GM recommends on change intervals. After all. Their the ones that designed the engine. I'm not big
on someone's opinion that aren't based on basic facts. They're not the one that's going to paying for the next
rebuild. You are.
.
In short. Think about it. Does this really make some
sense? Bob Dunahugh
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