Which Oil Will Provide Better Protection - 3k Dino or 6k Synth?

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Sep 18, 2003
San Francisco Bay Area
Roughly, which kind of motor oil will provide better protection - good conventional oil changed every 3,000 miles or any of the common synthetics changed every 6,000 miles? I calculated the cost of using dino and synthetic and it turns out that running one fill of synthetic oil for 6k miles costs about the same as changing conventional oil and filter twice in 6k miles. The difference was about $2. Also, with synthetic I wouldn't have to crawl under the car as much.
I have this idea that clean dino oil changed every 3k miles would be better for the motor than running dirty synthetic for 6k miles.

[ September 23, 2003, 08:51 PM: Message edited by: TheNauseator ]
Hard to say but if your only doing 3k mile drains, I'd run dino. Something like Pennzoil or Castrol GTX. Synlubes excell in high/low temp situations and extreme severe use such as towing, cold weather or racing....extended drains too.
My vote goes to the 3,000 mile conventional and not the synthetic, except exteme cold or hot weather operation.
I use synthetic in the winter only for its cold flow performance.
But, 5W20 mineral might do just as well a 5W30 synthetic in the cold performance department.
My vote goes with syn. This is one of the things I looked at when I considered changing, & based on all the info I could dig up, my opinion is that a premium full syn will provide better protection after 10k miles of use than a dino will after 3k miles.

At the time I was changing the oil in two cars every 3k, & that meant about 10 changes/yr for me. Going syn dropped that to 3/yr. But, I never would've switched if I thought my engines weren't being at least as well protected as with 3k mi dino changes.

[ September 23, 2003, 09:17 PM: Message edited by: Eiron ]
I just can't get excited about dino. I believe synthetic protects better, runs cleaner, flows better at low temps and, gives a performance margin of safety and, if I run a little long on an OCI, I believe it gives me a cushion of safety there too. When I consider all the unimportant (even if they are enjoyable) things that we (collective we) use our disposable income for, I don't fret about the extra I pay for synthetic when I think of the benefits it offers to that big expenditure sitting out in the garage.
I'd say one of the main advantages of changing your oil every 3k miles is that you can check to make sure everything is okay when you are underneath the car and also if you are leaking coolant into the crank case, you can spot is earlier. However, I know this does not occur very often, but is still a benefit. I myself have asked the same question over and over again which type of oil to use. I look at it this way:

5 quarts of Dino = $5.40 @ $1.08 ea.
5 quarts of Synthetic = $21.00 @ $4.20 ea.

Changing oil every 3k miles to me does not warrant the use of an oil filter greater than $3.00, so something like a Purolator Premium Plus or STP with a nitrile ADBV will do. So we are at $16.80 every 6,000 miles.
If going the distance with Synthetic where it will be in use for more than 2 season (fall, winter, spring), I would look for a quality oil filter with a silicon ADBV, something like a WIX filter which costs me ~$5.50. So that means $26.50 every 6,000 miles.
That's a cost difference of ~$9.70 every 6k miles. Not really worth it to me as a poor college student, but as Pscholte stated above, $9.70 a sunken cost that would inevitable go to something like bean burritos at your local Taco Bell . Taking an average distance traveled to be 12k miles per year, that is $19.40 per year. However, if I felt that sythetic oils can protect equal to or better than Dino oil up to say 8,000 miles, then I could justify the cost, but I have only seen a few UOA's where people have posted results with more than 8,000 miles. That is why I like what 3MadPonchos has been doing. It is tests like those that make me a believer.
If I had a brand new car, then I would use sythetic oil becuase of the relative value of the investment, thus I can warrant the additional cost.

[ September 24, 2003, 12:15 AM: Message edited by: HondaRD ]
Where is it written that dino oil has to be changed every 3,000 miles?
If that is a warranty requirement, than you cannot extend the service interval just because you decide to use synthetic oil.
You cannot judge an oil by its base oil group number. We've been through all that at least 20 times already.
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