hey everyone!
my question is: what kind of oil should i use? i have an '05 6i sport & i've been using FULL Synthetic 5w-20 (the type that the car requires) ever since i bought it brand new. i now have about 67k miles on it...should i switch to another type of oil? another weight? i understand that as an engine gets older you MAY need to change the type of oil to compensate for wear but i have read that higher mileage engines should be taken off full Synthetic because its TOO thin....what have you guys heard?? what exactly constitutes "higher milage"? ANY input is VERY appreciated...thanks to you all!!!

 

Those that say that synthetic oil is too thin don't have a clue as to what they're opining about. The fact is that weight for weight, synthetic oil is just as thick (or thin as the case may be) as conventional oil. Said another way, a 5W-20 synthetic will have virtually identical viscosity and flow characteristics as a 5W-20 conventional.

As for taking high mileage engines off of synthetic, hogwash. First off, at 67,000 miles your engine is just barely broken in (and hardly a high mileage engine). Second, many-many folks run their engines hundreds of thousands of miles on synthetic oil, and the only side-effect (such as it is) is that the engines usually outlast the rest of the car. My wife and I combined have driven nearly 1.7 million miles in cars lubricated exclusively with synthetic oil, and never once have any of my engines done anything but run and run and run. The last car I had prior to getting my Mazda3 ran 170,000 miles on synthetic oil, and when I traded the old girl in, she was getting ready to need lots of work, however, one of those work items was not the engine. That old mill was still only using a quart of oil every 7,500 miles, just as it did back when it was new.

So, long story short, if you want to use synthetic oil, then use synthetic oil. Period, full stop, the end.

 

In my 2007 6i, 2.3l, I use AMSOIL's 0w-20 with a K&N oil filter.

 

Full syn here. I race the damn thing and have yet to have any engine related problems. Though I have a 6s rather than an i.

-Cameron Keffer

 

Let the engine decide.
If the top up frequency is stable, and the old oil and filter cartridge seem in fair shape when they're changed, leave things as they are.
At 67,000 miles, if something goes wrong and you've followed what your owner's manual says, you have a good chance for some written or unwritten warranty benefit; if you don't do that, and something goes wrong, then a warranty issue puts you at a definite bargaining disadvantage.
People forget a few things about oil. First, as well as lubricating, it extracts a lot of unwanted heat from places water cooling can't access.
Second, if you up the viscosity for piston/ cylinder blow-by, (which as often as not is a valve guide wear issue anyway) or whatever, that viscosity increases the flow resistance through your oil galleries, crankshaft and bottom end bearing journals etc., so you make life more miserable for your main and connecting rod bearings.
My brother in law had a Mazda 323, and after his family grew too big, he gave it to his wife's parents. That car has been in the family for twenty three years and it was still going great, still using the same oil type it started with.
Call 67,000 miles, "high mileage"?
Why hell boy, your wheels ain't barely toilet trained yit!

But, for people considering going the other way, watch out.
if you start with conventional oil and put lots of miles on the engine, changing to synthetics/ detergent oils can cause problems.
The better cleaning properties can dislodge accumulated carbon, varnish, and gunk which was not doing any harm where it was, and then carry it in the lube stream to where it can do mischief.

If it ain't broke, don't fix it. And cars are just like people; it ain't good to mix their drinks.
If you have a valid reason to consider changing lubes, deal with that rather than mess with the oil. So there it is. Stay put.

 

Why all the old wives tales about synthetic oils in this day and age? They've been around for decades. A 5W-20 oil meeting grade SM is a 5W-20 oil meeting grade SM standards. Synthetic or dyno. How hard is that? Mazda says as long as the oil meets the standards and you adhere to the recommended service/change intervals, you're doing everything you're supposed to be doing.