Used protege5 from craigslist need help

[Protege5Here]

I recently bought an 03 mazda protege5 off of Craigslist. It is a 2.0 liter 4 cylinder engine. I've replaced spark plugs, PCV vlave, MAF sensor and fix the short ram intake the the guy had put on it. I also have done 2 oil changed sense and have put right about 1300 miles on it.
I replaced the oil sending unit do to lose of oil pressure. Since the day I bought it I've expierinced major oil burning. 150 miles and I'm 2 and a half quarts low. I tried a thicker concentration didn't help. I've got major white smoke cloud in the morning on first start or when it sits for a couple hours.
I was wondering if any one has any ideas on the oil leak. I was thinking valve seals and piston rings possibly.

I've also got and issue were when my speed decreases from 60 to 40 the rpms jump and I've got to throw it in netrual to stop that.

Any help I would greatly appreciate and just a general list of maintenance I should do. Its got 127,678 miles
Thank you

 

[Shkybonez]

I would do a compression check first to get a base line but from what I here the valve seats on these cars go bad around 130k

 

[Protege5Here]

What is the rated compression and what exactly would the test prove

 

[Maroon]

Does it have other symptoms? Is it running bad (low on power/misfire)? Why did you replace the ignition parts?

Oil burning from bad piston rings is common on this car. However, yours is extreme. Mine burns less than that (but it's bad), and I have 250,000 miles on it. My compression is good.

I don't recall the rated compression on this car. I think it is supposed to be around 180 psi from doing searches. A compression test is not a bad idea, but it won't necessarily tell you anything about your oil burning. That's why I ask if you have other symptoms. If it is running poorly, a compression test may shown that something is wrong in one of the cylinders (and that "something" could be head gasket, piston rings, or burnt valve). The first 2 can also cause oil burning. You can rent the tester from Autozone.

Link to someone else who did a compression test (but on a speed protg):
http://www.mazdas247.com/forum/showthread.php?123656589-compression-test

Not sure about the jumping RPM. Is it downshifting?

 

[MrGiggles]

My old engine was almost consuming that much, but had good compression across the board. The oil control rings do not have any affect on compression.

It's a common issue and seems to pop up on here at least once a month.

I opted to replace my engine, but another member (Lostincanada) replaced the rings with the engine still in the car pretty recently.

 

[pcb]

Compression info...

 

[KBrian]

If valve seals and valve seats are worn, one common symptom is blue smoke out the tailpipe when decelerating. White smoke is sometimes a symptom of burning coolant from a head gasket failure, that could cause oil burning. If the oil is milky on the dipstick or under the oil cap, this could also signal head gasket failure.
Maroon asked some very good questions about symptoms and when they started. I assume that there have been problems from the beginning of ownership.
Not sure if your car is automatic or manual transmission, but it's not likely to affect how much oil is used. Reducing speed by using the brakes, and then finding that the engine speeds up could be related to alot of things, including the MAF sensor, a vacuum leak, sticky throttle cable, dirty throttle body etc.
Doing a compression test is a good way to find out if all cylinders have the same compression. If one is more than 10% lower than the other three, this could be the source of your oil consumption problems. I would do a compression test first, then consider having a cylinder leak-down test done if the compression test does not highlight anything.