Midnite

I'm going to change my truck over to Chevron 5w40 synthetic from my current Chevron Delo 400 15w40. My plan is to use the new synthetic as makeup oil when I change both my full-flow and bypass filters twice a year. With the bypass filter my oil analysis has shown that I don't need to change my oil anymore because the filter changes result in enough fresh makeup oil that the additive package doesn't get depleted too far.

Anyhow, with my plan I'll be replacing 7 qts of oil in the entire 18 qt. system each time I do a filter change. This means that after the first filter change the oil will be a blend of 39% synthetic and 61% dino. With subsequent filter changes the system will gradually become full synthetic.

Has anyone here run a synthetic/dino blend for any reason, intentionally or not? Have you run into any issues or surprises?

Thanks,
Mike

SIXSLUG

My understanding is you want to run either/or, not a blend.

I would check out bobistheoilguy.com and wait for more responses from the guys and gals here....

Mike L

I am gonna go with SIXSLUG on this. I would bite the bullet and do a complete changeover, one time deal. I know 18qts is a lot, I just think that it would be the best choice.

Cheers!

Mike

DIESELWRKS

IF you are using blackstone for analysis you should call them. they are really up to speed on all the oils and if there will or would be a issue with doing a blend till its fully synthetic. I personally dont see an issue if this change would happen over the life of a filter change also this is depending too on analysis and how often those are happening. Also if I'm understanding you correctly why did you purchase or plan to go to synthetic if the current set up is working according to the analysis.

67HotRod

We tried changing a truck over from dino to synth oil and with the syn oil had to add 1qt every 500 miles.
Changed back to the dino and very little oil disappeared.

Midnite

Dieselwrks, I decided to change over to synthetic because it really helps with cold weather starts. I've got a little 125w pad heater on the bottom of the oil pan, so that helps--but only if I've got AC power nearby to plug into.

Checking with Blackstone is a good idea--I think I'll do that.

Thanks,
Mike

Busboy

Oil and filter is cheaper at ANY price than a gummed up engine, just saying. Since 2000 I've been changing my oil and filers every year and never add any between changes.

Midnite

Got the reply back from Blackstone and they say it should be perfectly fine.

They say they've never seen wear metals increase from any syn/dino blend, regardless of ratio. Also, apparently they've seen as much as 10 - 20% old oil remain when customers have tried to do a complete drain when moving to synthetic. I wouldn't have expected a percentage quite that high.

Anyhow, thanks for the responses.

Danderson

Mine's using a 1/2 qt every 3K now with Amsoil 15-40 Marine oil. I'll probably change the filter @ 4K,top it off and put another 4K on it.
Following that I'll return to dino 15-40.
I haven't seen any increase in fuel economy.
No leaks,just uses more oil.

JRMason

Synthetics have a higher amount of detergency then traditional dino oil and they clean all the carbon and sludge out of your engine that has been deposited by running dino for a long period of time. Sometimes the leaks will actually quit if you stick with synthetics for a few oil changes, and once the areas around the seals are cleaned they will swell up.

Sometimes the seals are old and dry enough they will continue to leak.

Running a synthetic will not net any increase in fuel economy. The advantages are superior protection in extreme heat/cold and heavy engine loads. The paybacks come with longer OCI once you establish a history with oil anaylisis.

gorms

My truck leaks, lot less with synthetic it seems. Just switched over back in the fall, has about 6k on it and I've only had to add 1 1/2 qts. Would be double that on regular 15w40...I can actually see rust forming on the oil pan now. Couldn't be happier with cold starts, will see how it does in the hot weather with a load on it.

SIXSLUG

bobistheoilguy.com....

KATOOM

Nothing wrong with doing research.....and Bob the oil guy is a great forum to look over.

Lots of good info out there on the internet but lots of misguiding info too. Especially with synthetic oils. One big misnomer is that people think synthetic is "man made" and isnt a petroleum product. For most off the shelf lubrication this is false. Excluding the obvious that the "final product" of all oil in your engine is man made, very few synthetic lubricant is completely man made and is really a petroleum base product. Which means that its COMPLETELY compatible with whats in your engine now. You can switch back and forth every oil change and there will be no affect on compatibility. But in regards to adding only a certain amount during a change is not a good idea because even though there's no compatibility issues, you should never run mixed oils in viscosity and brand. Just drain, change the filter, refill with what you want and you're done.

In regards to what makes a synthetic different, most synthetics recipes contain a plethora of man made ingredients along with the finest more symmetrically uniform hydrocarbon molecule stock pulled during the cracking process. Kinda like extra virgin olive oil is the best of other olive oil squeezes.....

So in saying that, synthetic tends to allow for increased lubrication properties which non-synthetic has a harder time achieving. Like low colder pour points for better initial start up lubrication and higher flash point resistance and coking in things like turbo bearings. This is why synthetics are more optimal in sub zero temps and can also be better under more extreme temp conditions. The lighter pour point means it can slip in the smaller spots easier so therefor it also has a tendency slip past rings and seals easier too. Other than that, to feel synthetic is the "best" is a result of good marketing. Lots of diesels out there with hundred of thousands or even millions of miles on convention oils. And some synthetics wont work as well as non-synthetics in certain applications. But again, its generally all petroleum base stock and all contains polymers which break down and sheer over time.


All I'm saying is, dont be misled..... Do your research and be schooled on the truth so you're not just taken for a ride by the savvy marketing dept.

SIXSLUG

^^^Thanks, Katoom! I think that my understanding was to not mix Synth with Dino, but I now remember it was about mixing viscosity's.

I quit worrying about switching to synthetic in the engine after I addressed the reality of what I use my truck for and realized I didn't really need it.

VADSLRAM

There are several dino / synth blends on the market. They attempt to give some of the benefits of the synth at a lower price.
There hasn't been an issue with blending the two types since the early 80s Mobile 1.
You can blend types and weights in an emergency. but they don't build on each other so once you blend you have only as good as the worst of the two.