Synthetic vs Mineral Oil
 

Okay guys, what are your general opinions about this? Do most of you use one or the other? What's is the interval between changes?

Could you switch back from Synthetic to Mineral or vice versa?

Are there clear cut studies that even at a 3000 mile per change interval, synthetic is better than mineral.

Any information would help. Thanks!!!

Generally synthetic has less impurities then dino. As such it has a larger changing interval. In general I stick to 7000-10000 for synthetic
and 3000-5000 for dino(manufacturers suggestions may very). It also tends to have a better operating range. That all being said, not all synthetics or dinos are created equal, as the additives make a huge difference in how long the oil lasts. So observation on which brand needs to be monitored.

Switching from synthetic to mineral is generally not suggested, though Im not quite up on why.

Mineral to synthetic, never switch to synthetic after about 60000-70000 miles. Either be on it the whole time or don't. A synthetic oil in an engine with those miles will find holes that regular oil wont find and will increase their size(speaking from personal experience).


This is the site everyone seems to recommend for oil recommendations per car http://www.bobistheoilguy.com/
They basically analyze the oil after use for the effectiveness of additives.

Use the front page for general info and the forums http://theoildrop.server101.com/cgi/ultimatebb.cgi
for asking or searching for your particular car.

All I know is that when the engine is new, its better to use Mineral oil. Up to 10 or 20k miles then switch to Synthetic.

Synthetics are also much more stable as they wear. As far as switching from dino to synthetic, i think there is a bit of a myth about that. I was running Castrol Syntec in my Z at 132,000 miles with no problems.

Synthetics do find holes that dinos don't, not too sure on wether or not they will expand them though, but it also sticks to the parts alot better when it's hot, which is what you want because the closer you get to metal-metal contact, the more dangerous it can get when heat needs to dissipate. Which is much more important in FI engines after shutdown when the engine goes into what is referred to as heatsoak, i.e. no airflow through the engine compartment, means the heat gets trapped under the hood and just builds up. this is the most dangerous time for a turbo or supercharger. Synthetics just work better here.

IMO, synthetics are much better than dino. especially when it comes to resisting the effects of blow-by gasses, as i mentioned with the stability in the higher mileage range :wink:

As someone who has personally lost money over just this situation I can verify this occurs. An easy verification is that it leaks with the synthetic and then continues to leak if you go back.

This is impurities and additive related. That being said, they can not be better then a dino version if their additive sucks. It really is a function of what they put in the oil. For example, Ive been told that the semi synth blend I started out with in my mazda is better then mobile one 10w30 synth which apparently has an outdated additive package. At the same time 10w20 mobile one apparently has a much better additive. Theres also a difference in formulas between regions and countries. That website I gave you has an area where you can send in oil samples from your car to be analyzed for the lowest content of harmful particulates.

i know my car didnt have synthetic blend in 'er when i bought it at 113k miles... and, immediately switched to, while adding a Lucas product for higher milage 'restore'.

i do know i do not burn, or leak any oil 20,000 miles later.

i know i can go further per oil change... so much so that i dont notice any more mpg after an oil change (tho noticed with diff and trans oil changes)

from what i've heard, if mixing dino and synthetic... the blend becomes more gel-like... but i havent tried to test this

what kind of car did this happen to gray? i've got to admit, this is the first time i've ever heard of the oil being the cause of eating way the engine :|

Depends of what car your driving, Synethtic is better but more expensive, but ifs a bomb just buy mineral oil and change it every 10,000KM. What ever oil you use, the more you change it the less engine wear you have. So even if you run mineral based oils your car will run good as a long as you change it frequently.

Best oil for far I used is, expensive but is awesome.
http://www.redlineoil.com/

97 pontiac grand prix se. Created a rather large leak in the oil pan. within 1000 miles of putting in synthetic. There was about 80000 miles on the odometer at the time.

Theres always an exception to the rule, but that doesnt make it a good idea. A friend of mine who owns an auto shop has had this identical experience with customers cars an absorbanent number of times. It really depends on the actual wear on the engine seals, but a general rule is about 70k.

The lighter viscousity of the synthetic coupled with its speed of movement especially at lower temperatures means it squeezes into tighter holes. If you squeeze fluid through a seal it will gradually increase the size of a hole.

put that way i can see where you're coming from. Baisically if you're going to switch from mineral to synthetic but have oil leaks, fix the leaks first :wink:

I thought you were trying to say the oil actually ate into the engine :lol:

Exactly, the holes usually exist in a high mileage engine at the seals.. the dino isnt small enough to go through the holes like the synthetic. The actual flow of the synthetic through the holes expands the holes.

synthetics can also help oil burnoff though. Being thicker than mineral at operating temps, it's harder for the oil to get by the valve seals and depending on how bad it is before the switch, it can temporarily stop burnoff due to worn oil control rings on the pistons.

i wouldn't suggest switching though if you're already dumping james bond like smoke screens everytime you go into decel :lol:

Better explanation from this site:
http://www.synlubes.com/about/faqs.html#7

which is baisically what we;ve been saying over the past 4 posts :wink:

Hey, Im just making sure Im being clear so it doesnt look like Im claiming it ate the engine.....

I have had a few beers and it is a 3 day weekend.. lol.