Well, reading through the manual I found some interesting things such as for temeratures below 0 deg. F you should use oil like 5W-30. For warmer temeratures for above 100 deg. F use 10W30 oil. It says that if you use 10W30 oil in colder temeratures then you may have problems starting the car.

 

I've been using 10w30 for all year. maybe I should change to 5w30 for next oil chage. but never had starting problem with 10w30.

 

Well, it says in the manual that they strongly recommend 5W10 for sub 0 deg. F temperatures. For extreme heat use 10W30. It does sound logical. My car would crank little longer (with a cold engine) when turning it on during winter.

Chris

 

Lighter oil is not just recommended in colder climates for easier cranking, but also because it gets to all parts of the engine faster upon startup. Those first few seconds after the car is started causes the majority of total engine wear. The faster the engine builds oil pressure, the less wear.

This is slightly off-topic, but that's why I try to combine multiple errands, and why I pre-fill my oil filter with some oil when installing a new one.

 

does using 10W30 for summer offer any advantage?

 

Read your car manual. 10W30 is better at higher temperatures while 5W30 is better at lower temperatures.

Chris

 

I agree, I've been using 5W-30 for the winter. We had a really cold spell a couple of weeks ago when temps were in the -20 to -10 range and I noticed that even the 5w-30 weight oil was starting to congeal in those conditions. I can't imagine how much harder the car would be to start with 10w-30.

 

synthetic or dino, and which brand?

 

Syntetic is generally better.

Chris

 

My $.02 on the whole issue is as follows:

if manufacturer specifies 5w30 why would you use 10w30.
thicker viscosity oils "on startup" give the starter added unecessary stress, therefore over the longrun shortening the starters life.

I use Castrol 5w30 semi synthetic and change at 5000 km or (3100miles) since the manual on my rx clearly states that "the use of synthetic oils does not extend the oil change interval".

The reason for semi synthetic is best of both worlds- quick oil distribution during extreme temperatures, and higher tollerance to thermal breakdown than conventional DINO type oil, and I am not paying the rediculous cost of fully synthetic oil.

Cheers,

Fern

 

my 98 GS4 manual says 5000 miles, not KM, or 7500 Miles, but doubt anyone does that

 

I use Mobil 1 15W-50 in my 99 RX, wanna guess why?

70K miles
Car is kept at 7,700 foot altitude with year-round temperatures averaging between 50 to 80F.
Mountain environment with steep inclines

5W-30 and 10W-30 are not even sold here and all distributors use a slightly higher weight than recommended due to the environment.

Moreover, 5W-30 and 10W-30 burn like crazy, synthetic or dyno.

 

Lex,

everyone is entitled to their opinion, and I certainly DON'T want to start a flame war however,

I disagree that oil consumption is effected by higher altitudes.
Yes, higher altitudes do affect performance, ie: 3% less performance for every 1000 feet above sea level.

Now,

Since it is a fact that most wear (in average vehicles- certain conditions excluded) occurs upon startup, I think by using 15w50 you may be doing more harm than good. Given the fact that the 15 of 15w50 represents the oil viscosity on startup (cold engine), you can see it is substantially thicker than 5 in 5w30.

Whether your engine has been subject to cavitation due to extreme operating conditions may also be a factor in the abnormal oil consumption.

Personally Lex,
given the high altitude, I would consider 5w50 or 5w40 which were created to resolve problems of thermal breakdown at extreme temperatures, while providing critical engine protection at startup. That said, anyone currently using 5w30 will notice added fuel consumption with the above oils due to the fact they are not energy conserving oils.

Hope this helps,
BTW Lex, beer is on me!

Cheers,

Fern

 

i'm going to run some Chevron Delo diesel engine oil for my AutoRX rinse cycle, it's 15W-40 too.

 

The RX oil specs I have seen are basically 5W-30 all year round in NA climes, so why debate it unless at high altitudes?