R Xplicit

i have been doing a study of oil usage in my car for the past 4-5 months, and i think that what you will find could be useful for you all. however, everyone's opinion will differ, but you will know whick way that i lean after this write up....

well, after deciding that 600-800 miles was too much for my car to be burning a quart to a quart and a half of oil, i decided to experiment.

here is what i have found.

jackson, ms avg temp since may ~85degrees in the day.
9500 miles logged on rebuild since 5-21-02

mobil 1 15-50 synthetic: burned AT LEAST 1qt. every ~950mi.
valvoline 20-50 synthetic: burned AT LEAST 1qt. every ~750-800mi.
amsoil 20-50 race syn.: burned AT LEAST 1qt. every ~800mi.

valvoline regular mineral oil 20-50 : burned LESS than 1qt over a 1400 mile period. oil still looked good, but i still change it every 2200-3000 miles...

mobil 1 20-50 regular : burned less than 1qt as well, under the sam circumstances as the valvoline.

i chose the valvoline because cam at pettit put it in my car after the new engine was installed and i trust his prefrences.

i definately know that the synthetice that heve gone into my car have all burned more rapidly than the regular types of oil. each one of these tests have been closely watched and documented. i decided to try this out because i simply got tired of seeing the oil light come on while halfway home on the interstate or sitting in traffic. these things concern me because my engine life sconcerns me as well.

i understand the ash content variables as well, and can tell you that the regular vs. the synthetic test i have done has its differences.

synthetic seems to burn slightly cleaner, but the sear amount that the car was going through as compare to the regular oil was proof enough for me.

i am going to stay with the regular oil for now. ****. i have been using the syn. oils for a few years now, but have a new outlook now.

synthetics are thinner, and yes can seep into the small areas better, but what about during the super high heat runs and cool downs. this is where the regular oil makes me more secure.

heat some up in a pan at the house. a side by side comparison will show you what i have seen and hopefully you will see my reasoning.

well that is it for now, but i am sure that i have other things that i can add but am simply forgetting....

add in your thoughts and reasoning as well. i know that this is an age old battle, full of opinions and differences, so lets hear them.

louis

R Xplicit

maybe no one cares, but oh well.....this does afect everyone....

louis

RotorMotorRX7

I use Castrol GTX right now. i got no complaints with that, and yes i do agree the mobil 1 my car EATS up!!!

93TTRX7

My valvoline lasts me more than any other brand i've used as well...i have just recently switched to castrol gtx though 10w-30 getting ready for fall and winter

R Xplicit

so it looks like a few more guys are seeing the same thing that i am, synthetic burns more rapidly. regular mineral oil lasts longer and coats better....

P'cola FD

Good info Louis. That an interesting way to look at it. I personally use mineral oil, just because I get it for free, and can change it as often as I like.

twokrx7

iTrader: (1)

I disagree that mineral oil coats better, it requires more polymer additive to get the multi-visc characteristics and this is likely what you observed in the frying pan.

In a motor, synthetic consumption may be higher, most likely due to thermal breakdown of the mineral oil or its add pack. I assume you've heard that synths result in a cleaner engine.

One thing to consider, rotary cars are tough on turbos. Quality synths are superior to mineral oils for thermal breakdown and varnish/sludge/coke buildup.

You asked for opinions.

cewrx7r1

iTrader: (2)

Since your engine was rebuilt this May, your oil consumption should be much lower for all the oils you tested.

I have about 18,000 miles on my rebuilt and it has been run only on Royal Purple after break-in on Castrol 20-50. The only time I had to add some oil between 2500 mile change, was when I was running a few dyno runs and much street testing under full boost.

If you are not running on boost a lot, then your engine has a problem.

A while back I had a Hayes rebuilt that was ****! It never got over 500 miles per quart no matter what I did. I junked the piece of trash and built my own. Mine is great.

Nathan Kwok

One thing that bothers me is how all the builders recommend 20w50 oil when the manual recommends 10w30. Your test reveals the reason I have always suspected, that a thicker oil will reduce the side effects of poor oil control sealing. Look at it like this: a new RX-7 back in '95 or whatever didn't burn 1 quart every 800 miles running 10w30, why should a rebuild need to run 20w50 to keep oil consumption in check? Yes I know 20w50 provides better protection under harsh conditions, but for everyday driving 10w30 should not only provide adequate protection, it should also do so without burning away so quickly. If a builder can only guarentee normal oil consumption when using 20w50 when the factory does it with 10w30, then clearly the rebuild isn't sealing as well as a new engine. This is probably just a fact of life, but I like to think a rebuild that uses lots of new parts should be as good as a brand new engine.

wishbanzai

Hew CEWRX7R1,
How is that royal purple stuff treating you? I used the stuff on my daily driver but was told that sythetics would get past the turbos and cause major oil burning.

paw140

Isn't synthetic oil more thermally stable? I thought that was one of its major advantages. If I were doing running at high temperatures, I would choose synthetic over dino oil.

Another thing to consider in your tests is that an engine will burn more oil than normal during the break-in period (at least piston engines do). Until everything seals and wears in properly, you are going to burn more oil. I agree that using a quart in less than 1000 miles is way too much. My stock engine with 90K doesn't seem to use any oil at all... at least the dipstick always reads full.

dubulup

My '95 doesn't eat too much Mobile 1 supersyn. 500 miles and dipstick still reads FULL.