Idle Roughness Fixed With 5W-30?
 

After reading about MazdaManiac’s study of the vacuum and oil weight at idle with his turbo system, I decided to try using 5W-30 RP rather than 5W-20. I wanted to see how it might help with the occasional stumble/studder at idle, espically with the A/C turned on. Not to mention the fact that its Hot as hell in Houston in the summer, so I figured the extra protection couldn’t hurt.

I can honestly say that the engine seems smoother after almost a month of use, I really don’t think about the idle now, probably the best test of how well its working. Occasionally I still notice after deceleration to a stop that it will stumble for a sec, but just sitting at a light, I hardly notice anything.

I always found it odd that older RX7’s seemed to have smoother idle than my car, which seemed weird. The old 7’s I think used an even heavier oil 20W-50, due to the heat? Which probably also sealed better. When you realize Mazda uses 5W-30 almost everywhere other than the U.S., it makes sense why the idle issue maybe hasn’t hit the radar for Mazda other than the U.S. For the longest time I just couldn’t figure out how the NVH folks would let the idle with the A/C slide.

It seems to me that keeping you MAF clean, good clean spark plugs, and 5W-30 will yield the best combination of smoothness and performance. 5W-30 is also more readily available. I don’t notice any fuel economy differences, but the actually difference from what I understand would be less that 0.30mpg, but for a fleet average, it helps Ford out.

If you have idle issues, give 5W-30 and a new set of plugs a try.

Any thoughts from you guys?

My 8 has had 5W 30 since its first oil change at the dealer so I can't give you a comparison but I had a first gen 7 and used 20W 50 Castrol and always wondered what was so different about the Renesis to generate such a different OEM oil need. (assume improved sealing in the Renesis??)

what plugs are you using with the RB plug wires?

at the moment the 8 plugs cuz the dealer replaced them for free, but I plan on using the 7 plugs going forward.

Alot of cars are going to lighter weight oil.

It's for emmissions. They burn cleaner with it. Plus the orfacies are getting smaller so they need the oil to pass through them.

brillo,

i have been running rp 5 30 for over 20k miles... it helps, but the plugs make a bigger difference.....

and the s flash even more..

beers :beer:

As far as my car goes -- I have the "R" flash... is "S" the absolute latest and greatest official one? Should I make an appt to get updated, or is this a flash that would be LESS favorable then my current "R" one

i would. it did not fix my big problem, but what it did for the idle is amazing..

beers :beer:

was using 5w/30 royal purple for long time, with 5w/20 car could not meet standard oil pressures listed in manuel (50.8). Manuel quoeted this pressure at 3k at 212F mine was 48/49 at 3 k at 180F, with the 30W no problems, ran pressure of 52-54. In the summer in Ga i am now running 10w/30 RP, --even better. On the track I use 40W, i also use premix all the time. engine is smooth, idle is good, temps are good, even in the Ga heat.
olddragger

OD,

what do you premix with?

I use lucas top cylinder lube(also has some injector cleaners in it) and yamaha motorcyle synthetic premix(Yamaha blue)oil mixed together at a 50/50 ratio. then i use the concentration as mentioned 1/2 oz to the gallon. Lot of good premix's out there. Just pick one. Just remember DO NOT USE a castor based pre mix of any type.
olddragger

i do have one. i would not premix with... on a fluke i picked up some belray syn racing.... it is thicker than the others i have used.... notice mpg is down by 2mpg..... after 3 tanks...

and the stuff was way to expensive..

beers :beer:

olddragger,
what would you recommend as the definitive choice for miami temps?
it's hot 10 months out of the year here...

I know hot in the south. I am in central Ga and today car ambiet tempt said 101F. While cruising on the interstate at 3.5K I saw my oil pressure at 54. I am running 10W30(experimenting with the 10W/30)royal Purple with a premix as previously mentioned. My water temp was 185 and my oil temp was 195. I would recommend:
1- synthetic oil (RP i prefer, but make your own choice, redline, amsoil etc).
2- 5w/30 all year long for us southern boys. If you track, go with a 40W. i was using 5w/30 on the track, before i put my gauges on and saw, but i am going to 5W/40 from now on.
3- I HIGHLY RECOMMEND PRE MIX FOR THIS CAR. especially southern cars. Mazda has recognized that the mop maps where not the best and the new flash is designed to help some with that. That is good but i think the way we drive these cars, i will still use pre mix
until proven otherwise.
sorry for the lenght of this but never ask an old man for his recommendations. we dont know when to shut up.
olddragger

Ok guys I guess I'm ignorant. What is "pre mix"? Please answer like I know nothing. I bought my 8 in Columbus, Ohio in April and I have just moved to Charlotte, NC and I'm wondering if I need to do more than the expensive stuff at Shell. Do I really need to switch to 5W30 at my next oil change? Any help is appreciated.

5W30 is the lightest oil I would use.I started using Castrol GTX 10W40 .With the turbo I decided to go Mobil 1 5W30.
You should be aware that the US and Canada are the only places on the planet where 5W20 is specified.

kevs,
premix is what you put in your gas, like a 2 stoke engine--do search function here--lots of info available.
olddragger