I use Rotella Synthetic in my '91 350SD. While, I like it and it lasts a lot longer, I notice more drips and leaks than I did with conventional oil.

QUESTION: Can I mix 1 gal Rotella Synthetic and 1 gal regular Rotella on my next oil change? I would think that this is similar to a blend.

Thoughts?

"R",

You are spending the extra bucks for synthetic benefits...why
dilute the lubricant? (weakest link in "blends" is the dino oil)

'make each "leak" a different weeks end project.

I have been using one quart of synthetic as an additive boost in oil changes for years. Forgot where I read the tip. Conventional oil is better than ever and exceeds the lubrication needs of most applications.

I have been in many refineries and seen lube oil from the same tank filling cans with various names on them. Same stuff, different additives, different names.

From my searches here I understand that there are more than a gazillion oil threads here and you can find more information than you would ever want to read. Many of those threads have links to bobistheoilguy.com

I will be surprized if you can notice a difference in your leaks by changing oils.

Without wishing to turn this post into a long involved Oil Thread, I would like to dispel the notion that the greatest advantage of Synthetic is that you can leave it in your engine for extended mileages. While that is indeed true, the best reason for using Synthetic Oil is its ability to adhere to metal surfaces (bearings, cylinder walls, etc.) which significantly reduces wear on your engine especially from cold start-ups.

Other advantages are:
- Better oil flow in cold temperatures.
- Greater resistance to viscosity breakdown in high temperatures.
- Better Additive package to suspend solids and extend oil life.
- Higher detergent content to keep oilways and internal engine surfaces clean.
- Additives to keep oil seals supple and extend their life.

That last point maybe in conflict with the common held notion that Synthetic Oil will cause leaks, but it is in fact true. What does happen (as I think 'bisric' has discovered) is that the Synthetic will loosen and suspend the accumulated sludge and coke from around the oil seals, which may have been preventing the seal from leaking. If the seal is truly bad then the oil will continue to leak but sometimes the additives that soften the seals will allow it to take up the clearance.

Bisric: I very much doubt that adding Dino oil to your synthetic will have any effect on leaking seals - which I assume was the purpose of your inquiry.

Sorry for the long post

Andy.

Most OTC synthetic blends are only 10-15% synthetic.

Rotella T 'synthetic' is not a true synthetic, as it is just hydrocracked petroleum slack wax (group III base), not a true synthesized PAO or ester basestock (group IV or V).

That said, conventional lubes are better than ever, and you would be better off making your own blend than buying one. The thing to worry about is that youre playing junior chemist, and something called 'additive clash' has been observed. Generally though, oils from the same manufacturer in the same family line are OK.

However, if I can make a suggestion, Rotella T fake synthetic is a good deal at $12.88/gal at wal mart. However, rotella conventional is a very ordinary oil. Mobil delvac 1300 has the best aditive package of all HDEOs, and chevron delo has the best basestock (very similar to the rotella T synth, and its actually called a group II+). I did very well protection and mileage wise by making a blend of delvac 1300 with delvac 1 synthetic (or you can now get it as mobil 1 truck & suv - exact same stuff!)

Delvac 1 is the best synthetic oil available.

JMH

__________________
Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (116k)
1991 350SD (206k)
1991 300D (228k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (267k)

Past Diesels:
1983 300D (228K), 1985 300D (233K), 1993 300D 2.5T (338k), 1993 300SD (291k)