Fully synthetic or Dura-blend? - Off-Road Forums & Discussion Groups
Ford 67-96 F-Series, 78-96 Bronco All discussions of 67-96 F-Series Trucks and 78-96 Broncos

LinkBack Thread Tools Display Modes
post #1 of (permalink) Old 01-28-2003, 10:45 PM
Posts: n/a
Fully synthetic or Dura-blend?

I am tryin to figure out first of all if I even want to switch to synthetic oil. I've heard that it shrinks the gaskets causing leaks, but I don't know if thats true or not. My truck has 68,000 miles on it and has had only reg oil in it every 2,500 - 3,000 miles. So do yall think switching to synthetic is worth the extra money? and if I do should I use full synthetic or dura-blend? Would it do more good or bad to my engine? [img]images/graemlins/wink.gif[/img]
Sponsored Links
post #2 of (permalink) Old 01-28-2003, 11:28 PM
Join Date: Dec 2001
Posts: 4,011
Thanks: 0
Thanked 0 Times in 0 Posts
Re: Fully synthetic or Dura-blend?

Some people swear by them. Personally I believe if you change or oil often then there is no need for synthetics. However if you are one to let the chore slide then synthetics are for you. I've heard that there are some benefits to be gained HP wise but for a 4x4 I don't think the gains would outweigh the cost. I don't think most of us run our oil hard untill it is a froth anyway. Just my .02 [img]images/graemlins/smile.gif[/img] NORM
BigNorm is offline  
post #3 of (permalink) Old 01-29-2003, 12:59 PM
WD40's Avatar
Join Date: Apr 2001
Location: Helena, MT
Posts: 2,280
Thanks: 0
Thanked 0 Times in 0 Posts
Re: Fully synthetic or Dura-blend?

I've heard that it shrinks the gaskets causing leaks,
It doesn't shrink the gaskets.
The leaks show up because it's so much slicker (more viscous) than regular oil.
Regular oil, over time, will attack the gaskets (especially the cork ones) and basically eat at them till there's nothing left.
What keeps the engine from leaking oil is sludge build-up around those gasket voids.
A lot of times, swapping in fully synthetic oil (or, even a high detergent oil, like Kendall) under those conditions,
will clean out the sludge, and leak past the voids in the gaskets. [img]images/graemlins/frown.gif[/img]

Synthetic oil on the other hand, does not attack gaskets what-so-ever.
If you start using it, once the engine is broken in properly, you'll never develop any oil leaks. [img]images/graemlins/cool.gif[/img]

Sorry, rambling.
Your's at 68,000 is just getting to the edge of not taking kindly to fully synthetic.
You'll probably develop leaks.
Valvoline Dura-Blend (semi-synthetic) is great stuff, and should work excellent in your case.
I think you'd be surprised by running an oil change with that.
What brand/weight have you been using?

I use Mobil 1 exclusively.
But, that's because I started using it after a proper 6,000 mile break-in period.
It flows extremely well in our cold temperatures here in the winter.
WD40 is offline  
Sponsored Links
post #4 of (permalink) Old 01-29-2003, 03:45 PM
Join Date: Sep 2000
Posts: 1,147
Thanks: 0
Thanked 0 Times in 0 Posts
Re: Fully synthetic or Dura-blend?

Do a search as there's a couple of good threads on this subject

I switched to fully synthetic up in the Arctic with 180,000 miles on her and experienced no leaks. That said, when I stuck it in the new longblock, after the break-in period, it started to gum up the engine and I experience "blowby!"

I tell you I was in a bit of a panic ! I'd always used synthetic in my smallblock Mopars, but this 302 seemd to sludge up real fasy with it. I took peoples advice here and changed the oil 3 times in a row, after only 600 miles and washed out the slidge. After I'd changed the oil breather, PCV and soaked air filter, it finally stopped the blowby.

Now I do like they say and change with anybodies 10W30 every 2000 miles.


I am a firm believer in synthetics everywhere else on the truck. I run Mopar high performance 85W90 in both axles, Castrol fully synthetic Dexron III in the transfer case, Valvoline fully synthetic power steering fluid and I was running the Castrol in the tranny, but I can't afford to anymore, so it's regular Dexron III in the AOD. The next project is to install a remote tranny filter next to my B&M tranny cooler.
Sixlitre is offline  
post #5 of (permalink) Old 01-29-2003, 04:23 PM
Join Date: Mar 2002
Posts: 200
Thanks: 0
Thanked 0 Times in 0 Posts
Re: Fully synthetic or Dura-blend?

In a 92 Z-71 that I bought with 96,000 miles I switched to Mobil 1. I know for a fact it had castrol run through it for the first 96,000 miles. In roughly 35,000 miles I experienced zero leaks on anything. Only thing I noticed is that it ran a bit cooler. I've actually switched to Mobil 1 on 4 different cars and trucks and have experienced zero leaks. These are just my experiences with normal oil and Mobil 1. My wifes 4-Runner (96,+++) and my Bronco (169,+++) have had Mobil 1 run in them since the second oil change. I change my wifes oil every 6,000 miles and you would not belive how clean it is everytime I change it. It looks like it just came out of the jug up to about 4,500 miles than it starts getting a little dark--gotta love Yota engines. On my Bronco it starts getting dark after about 2,000 miles and even at 4,000 miles when I change it the oil looks great. I guess I should say I truely believe in Mobil 1--been using it for 14 years now. Sorry for the long post.


msuforeman is offline  
post #6 of (permalink) Old 01-29-2003, 05:30 PM
Join Date: Oct 2001
Posts: 2,508
Thanks: 0
Thanked 0 Times in 0 Posts
Re: Fully synthetic or Dura-blend?

Well this post is bound to bring the many fors/againsts as it has been debated as long as the synthetics have been around.

I believe in synthetics. I do not believe in paying for them. If you are a fanatic like me and change the oil/filter every 3k, this is most important. I like value, and so use Valvoline maxlife, 5w-30 per manuf. spec. The filter is just as important as there have been many posts/discussions on good and maybe not so good filters.

Now, if your vehicle is in Virginia, then you do not experience Canadian, Alaskan, or even Montana Winters [img]images/graemlins/wink.gif[/img] which provides some added justification to these folks possibly needing the added flow benenfits of a synthetic. Heck, they may also wish to run a different viscosity for summer /winter but that is another topic.

Also, if you have a nice, newly rebuilt motor there might be something said for sythetic. But added HP and mileage....well maybe vs. the same viscosity dino oil, but the cost of sythetic will outweigh the possible savings.

I also am not a believer in extended oil intervals, no matter what you run. Besides it gets expensive replacing sythetics in different components such as axle fluid every time you think you may have gone too deep in the drink...right REP-T?? [img]images/graemlins/blush.gif[/img] [img]images/graemlins/grin.gif[/img]

The only synthetic I bought was for the grease gun, and I still use as much and as often as I did before.

Just one more Opineeeeuunnnnn.
TheJuice is offline  
Sponsored Links

Quick Reply

Register Now

In order to be able to post messages on the Off-Road Forums & Discussion Groups forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome