Are there any accurate consensus of opinions (founded by fact & engineering)
on when it is best to change over to synthetic engine oil. Since I am an Amsoil dealer, I want to use it but will wait until the recommended amount of miles/hours on the vehicle before doing so.

Thanks,

Dave
05 Silverado CC LT DMax

I don't know that you'll find any "engineering concensus" but most here agree to wait until 10,000 miles to switch..

I do the first oil change @ 3k and It's moblie 1 5W40 delvac syn, no issues in 200k combined. FIW

Waiting 10k is a myth. Too many cars coming from the manufacturer with synthetic in them, and no problems.

1500 miles on mine, and I just went synthetic.

I changed to synthetic and my oil consumption went way up. I switched back to dino and the oil consumption is dropping.

YMMV,

Jim

I thought the idea was to run 10K on dino oil, and let the diesel engine "break in"; once it has broken in, then you switch to synthetic. I had been told that this is what helped fuel mileage increase after the 10K break-in period, and that if you used synthetic before this, your mileage wouldn't go up because the engine didn't have a chance to break in properly.

Is this wrong?

Joseph

Well, since my wear rates are slightly higher when I use synthetic, I would think you'd be better off switching over right away to help that Duramax "break in". I'm not trying to be a smart-a$$, either. That's just my observation after 7 UOAs on my truck.

I also think it's bull**** to wait to put synthetic in. I also think it's B.S. that synthetic is automatically better than dino.

Let used oil analysis be your guide--that's no B.S.

Changed mine at 2300 miles. I now have 40K on it and not a problem. This last 10K was towing and it only dropped about a 1/2 a quart. Will be running it as long as possible by using used oil analysis.

Greg

I thought..at one time....that synthetic oil was causing my oil consumption. I would start burning oil on my LB7 at 4k miles.

Well I now drain the oil completely by raising the front end of the truck up...I get another quart out...I also have the fumoto valve.

I have been running Amsoil 5W-30...with 8500 miles on it and OLM saying I have 23% left.....I have not used a drop.

When OLM says 5% I will pull a sample for analysis and replace oil....just to see if the OLM and analysis jive.

But I think Synthetic is fine....but raise the front of the truck to drain all of old oil out.

???? You thought synthetic was causing oil burning, so you switched to synthetic 10W-30. I'm lost:confused:

No....I saw others mentioned about having to raise the truck for a better drain....and that remants of old oil could cause oil consumption.

Soooo I tried it doing just that and found I had oil in there that I was not draining out.

Therefore....before changing from synthetic...I performed a more complete drain....result...while still on synthetic...no more oil consumption.

Ya still lost?

Just changed to synthetic for first oil change @2500. DIC said 50% oil life. I used Mobil 1 5W40 (light truck and SUV). 10 quarts. I noticed an increase in gas mileage right away. Up to 14.8 from 14.3 (heavy foot short commute). Synthetic is the cheapest insurance you can buy. My wife's suburban lost all of its coolant and no idiot light came on. Driving though the White Mountains I could smell something burning, the spark plug wires were melting the engine was so hot. I am convinced the synthetic saved the engine.

I've used Amsoil since 1980, always changed over at the 1st oil change at about 3K. Never had an oil burner even at 200K on the engine. Sometimes you may get some blowby early on because the rings haven't seated yet (esp. if towing). With many high performance engines and drivetrains coming with synthetic from the factory its obviously not a problem.

...I also have the fumoto valve.

I have been running Amsoil 5W-30...with 8500 miles on it and OLM saying I have 23% left.....I have not used a drop.

When OLM says 5% I will pull a sample for analysis and replace oil....just to see if the OLM and analysis jive.

But I think Synthetic is fine....but raise the front of the truck to drain all of old oil out.

What is a fumoto valve? Haven't heard that one yet?

After reading the Duramax manual, they recommend 15W-40 for running in temps over 100 degrees. Here in the Southwest we see those temps all the time in the summer. For me, I think the 5W-30 is a little too light.

I think the oil analysis is a great idea, however I a firm believer that clean oil is a happy engine. I'll change mine every six months after break-in, probably much sooner until then.

Dave
05 Silverado CC LT DMax

I thought..at one time....that synthetic oil was causing my oil consumption. I would start burning oil on my LB7 at 4k miles.

Well I now drain the oil completely by raising the front end of the truck up...I get another quart out...I also have the fumoto valve.

I have been running Amsoil 5W-30...with 8500 miles on it and OLM saying I have 23% left.....I have not used a drop.

When OLM says 5% I will pull a sample for analysis and replace oil....just to see if the OLM and analysis jive.

But I think Synthetic is fine....but raise the front of the truck to drain all of old oil out.

How high do you have to raise the front end?

www.fumotovalve.com heres the link for it

Since I have the valve...I can start draining while the truck is running or just after a long run. I highly recommend all to get this valve...oil changes are soo much easier.

I think I am raising the front wheels a few inches....but since the oil is hot....I can tell by raising a few more clicks on the floor jack after the oil stops running.

I use the old Amsoil 10 qt container to empty my drained oil...and now I get a full 9.5 quarts or so drained amount plus whats in the filter.

As far as the the 5W-30 being too light an oil...I will see with oil analysis....I have seen the ford 6.0l do well on this oil...if not I will go back to 15w-40.