10W30 or 20W50
 

So I was talking to this gy and he told me that I should consider putting 20W50 in my engine for the next oil change instead of the 10W30.

IS there anything bad that can happen with a heavier oil? Or would it be a better idea? Not thinking so since winter is approaching soon.

less wear, more drag.

only use thicker oil if it's necessary, such as on an old tired engine with questionable life left and decreasing oil pressure. otherwise if everything feels and looks good, stick with a thinner oil. 10W40 is a decent compromise in summer but 20W50 is fairly thick.

I thought everyone runs 20w50 year round if the temp is right and they're a spirited driver.

I've only ran 10w30 in winter and that was when I lived up north where I saw freezing temps.

So im due for an oil change. Should I get some 20w50 or just stick with 10w30 because its going to get pretty cold here in NC soon

The 2nd Gen FAQ has a link to free online service manuals. In Chapter 2 there is a chart showing which viscosity to use for a given outside air temperature range.

Basically, the lower the number before the W, the better the oil will flow during starts in cold weather, reducing wear. The higher the number after the W, the better the oil will protect against heat and shock, but the power and gas mileage will be slightly less due to the thicker oil.

That helps a ton. Thanks alot. I guess i never thought to read the FAQs..... thanks again ill keep it in mind for future reference

When I first got my RX7, I went out and bought 5 quart jugs of Castrol GTX 10w-30 at Wal-Mart and then realized it maybe a bit thin for summer spirited driving or for use at track day events. So I bough some Castrol GTX 20w-50 and was mixing the two 50/50 - sort of like a home brew 15w-40 (which is a typical diesel weight). Afterwards I just switched to Castrol GTX 10w-40.

oh boy!, another oil thread!..
(Rolls big Dubey and pops 10 valium)..please continue!

"Dubey"?

How about this; invest in an aftermarket oil pressure and oil temperature gauge, try to get your pressures as close to 30psi at idle and 60psi off idle. Also note how oil temperature effects pressure to yourself, with that knowledge you can figure out when you need to swap out for a thicker viscosity and vice versa.

heh..I Kan't spel aftir 10 nvaliummmmmmmm...loook a bunny...

One thing I read in my "oiling" adventures on the interweb is for us, oils like 10w40 subject the motor to higher ash content and carbon build up. Definite no no from what I can understand. I loved using 15w40 since it seemed like such a nice compromise... Until I lost a motor from a carbon stuck seal :(

AND I was premixing!

now I just stick with normal old 20w50 :) happy with it. Also using Idemitsu now!

I was also told that I should change the filter for the 3rd gen filter instead of the 2nd gen one to raise the oil pressure. Is this logical to do or should i stick with the regular filter?

I still have regrets from switching/running 20w50 in my low mileage car, just because Im not sure it was a good thing to do... I was getting a rear main seal leak from the PO 10w30, and plus I live in Texas..... I take my time warming it up and have an aftermarket oil pressure gauge...

So you regret switching from 20w50 to 10w30? OR visa versa?

10w/30 year round in my high mileage NA.
Works for her, works for me.

I studied all the manuals and looked at my temp ranges where I live in... when I first got the car, I could already see a rear main seal leak, and the PO said he would ONLY RUN 10w30 in the car (Granted, this is someone who NEVER NEVER drove the car, and last time it *might* have been driven, it was in california or oregon...)

My mechanic friend who was doing the maint on it said to switch to 20w50 for our texas heat, and to keep the rear main leak at bay... FF 4-5 years later, Im about 3 months away from planning an oil pan and rear main seal replacement... starting to leak again...


Im just a VERY OCD person, so I get afraid im tearing up my "pristine" motor by running 20w50... feels like a "system shock" to a car thats been sitting its whole life... but it IS HOT in texas, and I baby the crap out of it until I get to about 70-80c

(Yes, I said c. my gauges dont read F, and I already did the math once to figure out what those temps mean... so around 75-90c the car is good and fun. I have yet to hook up my coolant temp sensor, but thats another story, I digress.)

I think oil filters are same for 1st, 2nd and 3rd gen. Even for 04-08 RX8 used the same filters from RX7

I was told to use a low profile filter instead of the larger one. I guess I'll just doc the change with the normal filter

Your "Texas heat" is only relevant to the extent that it affects your car's heat handling capabilities.
For a couple of years I ran side-by-side oil temp, oil pressure and water temp gauges and hawkeyed the relationship between the three.
Oil temp was @ 15-20° F higher than water temp, regardless of the weight of the installed oil or ambient temp.

My conclusion was that my engine worked fine with the lighter weight oil and saw no cooling improvement with 20w/50, so why use it?
Mysteriously, both times I've tried 20w/50 lately the car smokes excessively, something she hardly ever does with 10w/30.
No clue why.

Get yourself a real water temp gauge (if you haven't already) and monitor the temp closely. You can't have excessive oil temp and good water temp at the same time, so if the coolant is fine, so is the oil.
Run the lightest weight you can get away with.

Can I still switch back to 10w30/10w40? Or will I start to leak like the Valdez from every corner? Ive seen different people cringe when I mention switching back, so Im scared to try it...
For almost 20 years the car has been sitting at 9k miles with the 10w30... its only the last 4ish years Ive racked it up to 26k with 20w50....

(As for the water temp gauge, I have as real of a one you can get... I just prefer to install the sensor into my water pump housing. Something I have done, but I have yet to install the HOUSING... ugh)

Dunno, but I'd try it and see.
Seems like if the only thing holding in your oil is its weight, you have other issues.

Clokker is right.

I'm actually finding myself doing my own research, and I actually feel terrible for running 20w50, I want to go to 10w40..... In-fact.... (Im still doing research, and I hope these "smart" people I'm reading about are actually smart...) I think I want to try 0w40...

i don't necessarily agree that a thinner oil protects more on startups, lighter weight oils will runoff of parts quicker, giving less protection until the oil begins to flow again.

I neither agree nor disagree, any dog I had in that hunt long ago wandered off to lick his balls.

I am much more pragmatic and simply pay attention to the car...she smokes like a chimney with 20w/50 and not at all with 10w/30. Water temp and oil pressure are the same either way, so I'm just going with the flow.
With 250+ K on the clock, it's useless to worry about "cold start oil protection" or "long term wear" anyway.