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Discussion Starter #1
I've always ran your typical conventional diesel oil. It's time for another change and I consider my truck to have quite a few miles on her (219k) so I'm gonna switch over to synthetics. Have a few questions.

Are all syn pretty much the same? Ams vs schaeffer vs valvoline etc?
What weight should I get?
For those of you that have switched what did you notice?
I've heard that once you go synthetic you can't switch back? Also heard syn can seal up leaks? Any truth to that?

Sorry for the newb questions, i've never looked into syn till now.
 

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Haters Gonna Hate
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try out some mystic in the ol girl myles, i love it in my pickup, diff motor but same principal on the high pressure oil, im running 10w30 in mine bout 22$ a gallon, and synthetics wont stop leaks
 

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Yeah I'm gonna add in a little additive to the oil when I change it.

I'm still tryin to figure out what oil I'm gonna go with.

Anybody care to elaborate on differences between conventional and synthetic on start ups, idle quality, etc...
 

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Discussion Starter #4
Yeah I'm gonna add in a little additive to the oil when I change it.

I'm still tryin to figure out what oil I'm gonna go with.

Anybody care to elaborate on differences between conventional and synthetic on start ups, idle quality, etc...
 

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Haters Gonna Hate
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your idle will be much smoother and slightly quieter than it is right now when u switch to synthetic, and from what ive read i wouldn't put any additive in your oil, the high pressure oil system will cause it to foam, there was a thread awhile back on lucas that says on the back is made specifically for powerstrokes, its a synthetic base and it foamed also, which knowing what u know means bad news
 

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Exploding the magma
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I've always ran your typical conventional diesel oil. It's time for another change and I consider my truck to have quite a few miles on her (219k) so I'm gonna switch over to synthetics. Have a few questions.

Are all syn pretty much the same? Ams vs schaeffer vs valvoline etc?
What weight should I get?
For those of you that have switched what did you notice?
I've heard that once you go synthetic you can't switch back? Also heard syn can seal up leaks? Any truth to that?

Sorry for the newb questions, i've never looked into syn till now.
Amsoil is a group 4, hence the price. Also most of their oil is CI-4+ more tbn but CJ-4 does better against soot. Rotella, Valvoline and most other brands are group three. On a 7.3 a 5w40 will make a world of difference starting in the cold. In the summer they don't make too much of a differnce IMHO. I go back and forth between synthetics and dino all the time at 190k miles and no problems.
 

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Discussion Starter #7
Amsoil is a group 4, hence the price. Also most of their oil is CI-4+ more tbn but CJ-4 does better against soot. Rotella, Valvoline and most other brands are group three. On a 7.3 a 5w40 will make a world of difference starting in the cold. In the summer they don't make too much of a differnce IMHO. I go back and forth between synthetics and dino all the time at 190k miles and no problems.
This is the kind of info I was looking for. Thanks.

Any other info you guys can give me?
 

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As far as the myth that once you change to syn you can't go back............Just a myth. You may change back and forth as you please. Syns are compatible with conventional oil.

Syns cause leaks isn't a myth but isn't true in all cases either. Huh......Why is that you ask? When syns first came out for general public use people were putting them in cars that had not been taken care of very well. There was a lot of sludge build up in these cars and the sludge would keep seals that were bad from leaking. Syn oils have higher detergent concentrations and would clean that sludge thus exposing the bad seals that were being held closed with sludge. For those that took care of their vehicles it wasn't an issue. If you have bad seals already syn may cause them to leak if your in good mechanical condition you will have no ill effects switching.

Synthetics will improve your mileage by approx 5% which is 1/2 mpg on a truck getting 16 mpg already. Syn will stand up to more heat and colder weather better providing better cold start ups and better protection when towing in the hot months.

Synthetics will allow you to extend your oil change interval (OCI) greatly in a 7.3. I will be honest with you even though I sell Amsoil, in a 6.0L I would not go past 7500 miles without UOA due to the shearing tendencies of the 6.0L. I have many customers that do 10k mile oil changes in a 6.0L and some without UOA with no ill effects. I just don't recommend it without UOA which is cheap insurance.

I have plenty of 7.3L customers doing 15-20K mile OCI and some going much further using a dual bypass system.

Are all Syns the same? No..........synthetics are made from different base stocks and have different additive packages added to them for different results based on the needs of each comapny. There are Group III, Group IV and Group V base stocks in synthetics. Many cheaper synthetics are made with Group III base stocks which are the lowest level base stock allowed to be used and call it a full syn. Many Syn Blends are also Group III. Group IV is a more expensive base stock and depending on who you talk to and what research you do are considered the best base stock to use for a synthetic oil.

In your 1999 7.3L I would recommend either a CI-4 15W-40 (first choice) or a CJ-4 5w-40 depending on your climate and needs.

Without giving you a day long disertation on oils I hope that has answered some questions. If you would like to consult me about using Amsoil shoot me a PM with your questions and I can answer them to the best of my knowledge.

Dane
 
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