Oil Viscosity?

[Sophia69IS]

Hey I tried to search the forums for the answer for this, but I think the search tool is messed up.


I've been running 5W-30, but this dumb little computer at Wal-Mart said that I amsuppsed to be running 15W-40

What is the correct viscosity for the M42??

Thanks!

[DesktopDave]

It depends on the season for me.  But I have also run cheaper synthetics like Mobil1 and Syntec (whichever is on sale) 10w40 year 'round.  I might change out for a thinner synth 5w30 or 0w20 in the winter months, but I've never noted a difference.  Synthetic is so much better at cold starts that the visco range isn't really critical.

I'd avoid the really wide visco ranges like 5w50 because the visco modifiers will degrade the oil's lubrication significantly over time.

Most newer cars will use really thin oil year round to pick up a few MPG.  My Mazda MPV with the Ford 3.0 V6 specifies 5w20 IIRC.

[Sophia69IS]

Thanks for your advice!

I usually run 5W-30 year round and change every 3000 miles. But I use conventional oil. Pennzoil to be specific. Haven't had a problem with it, just after 3000 miles it is always black as the devils dick.

[tjts1]

5w40 to 15w50 depending on your climate.

[DesktopDave]

I usually run synthetic oil for 6-9k mile intervals, but I change the filter every season or 3k miles.  I did note slightly better fuel mileage after I changed out all the oils with synthetic blends.  It's still a noisy car though.  Pennzoil Platinum is a nice synth blend...I've had that in the cars for a while now.

Every oil change I've done has had black oil.  That's a good thing...if it's not picking up the contaminants, the oil detergents aren't doing their job.

I'd suggest using 'real' Group IV PAO synthetics to fill the gearbox & diff, like RedLine, Amsoil, etc.  The others are usually Group III petro oils that aren't as good.  They'll say something like "except for carrier oils" on the bottle but not specify what percentage is synthetic.

[BlueBMW]

I've been using the bmw (castrol) synthetic 5w30 every 5000 miles or so.  I only use it since I can get a near limitless supply from work.  Free is good!

[Sophia69IS]

Hmmmm.....that is interesting, I guess I maybe should try a thicker oil since I live in South Carolina now and it is very warm here?

Plus my motor has very high mileage....anyone run "high mileage" oil in their cars? Is it really worth it?

Have any of you running synthetics had a problem switching from conventional to synthetic with your seals??

[PumpItUp]

I'm running Mobil 1 synthetic high mileage since there was a good sale and I didn't want to build up any new sludge running conventional after working hard to clean the intake manifold, oil pan, etc during the heater plate delete & pan bolts check. the high mileage variety was the same price so i figured what the hell, even though my car is still under 120k. i don't think it's any different, just advertising. some say mobil 1 isn't even truly synthetic, just conventional processed a lot. i noticed the stuff stays clean a lot longer, but oil that gets darker from its original yellow isn't necessarily from friction. again, i don't know what to tell you, when i used lubro moly, seafoam, and other 'cleaning' products, i was very impressed and can tell it from other junk at parts stores. but for oil, i don't have a labratory to test it. No my car didn't leak a drop. i think the only conclusions i can make is
-it doesn't cause as much sludge, especially from pcv hose
-it has a longer interval between oil changes
-it costs more

any performance gains (using the same 10w40) I can't prove since I cleaned my injectors,etc

[Sophia69IS]

Ya I think the high mileage was $1.00 more than the regular. There is no sort of explaination as to why it is better or the reason that you should use it other than it says "high mileage" on it for vehicles 75,000+ miles.

I do not have any experience with synthetics. Your car does not leak at all?? I am very jealous. haha.

120k? your engine is practically brand new.....I'm running 268,000+
but I drive her everyday.

[tjts1]

Hmmmm.....that is interesting, I guess I maybe should try a thicker oil since I live in South Carolina now and it is very warm here?

There is no reason to use 5w30 in this engine unless you live in alaska some other place where the temp stays way below freezing for months on end.

[Sophia69IS]

^^ What oil do you suggest?

And yes it is very warm here. =P

[tjts1]

Rotella 5w40 synthetic in at gallon jug at walmart. I think its $19/gallon. Its good for year round use even if you have freezing temps at night in the winter. I keep it in there for ~5-7k miles depending how lazy I get. 15w50 synthetic if you rarely experience freezing temps.

[kenika65]

50w all the way no other option in my opinion

[Sophia69IS]

^ just 50W?

tjts1: what do you think of synthetic vs. conventional....i've heard bad things about switching on an older engine.

[P. Kennedy]

There is a recommendation on this very forum, from an actively employed petro-chemist, no less, for the Shell Rotella 5W-40.  He was somewhere on the Eastern seaboard if I remember correctly, fairly far North, not down in the Carolinas.
The Rotella was his 2nd choice to Amsoil European Formula 5W-40 which is pricey and hard to find.