5w30 vs 5w40..

[MatthewDavid]

Hey guys... our mark's oil light came on so I told my gf to throw in some Mobil one... well I told her 5w30 and she got 5w40... I doubt this will do any harm since they're the same weight... but what does that second number mean?... an just in case is it alright thanks!

 

[brentalan]

It won't hurt anything especially if it is just one quart. The 2nd number is the thickness at operating temperature. So what you put in is a a little thicker when the car is up to temp. There is actually a TSB from Ford that recommends using 5W-20 the Mark VIII. I would suggest using that at your next oil change. It may give you a LITTLE bit better fuel mileage.

 

[whiplash15]

Oil weight ie "5" w "30" is determined by the rate that the oil will drip off of a metal sheet at a given temp. So, 5w30 drips as slow as 30 weight at a high temp but not any faster than 5 weight at a low temp.

 

[MatthewDavid]

Hmmm... it's all about the drippage huh that's good to know... yeah it's about do for a change... I'll take your guy's advice and throw in the 5W 20... I could always use the extra mileage... Thanks!!!

 

[unity]

In colder climates, 20w is probably better. In warmer climates or during summer a 30w is fine and in some cases even a 40w would be ok.

 

[mespock]

And if you add some nice thick Lucus???

 

[chicken]

And if you add some nice thick Lucus???

then you have a foamy mess, now i gotta find the link, some guy made a tester, like what they have in the stores but with a electric motor on a speed controller, that spun 2 of the gear sets, and oil alone was better in every situation, that lucas crap turned to foam.
and for those that dont know, foam=small bubbles in oil, small bubbles=air, air=no oil=bad

 

[unity]

"foam=small bubbles in oil, small bubbles=air, air=no oil=bad"

LMAO!

 

[Roadboss]

The lighter weight oils are also specified because of the smaller clearances that are run on these engines (giving them longer life). Race engines with alot more clearances typically use a more viscose(higher weight #) oil. Our modern day engines are machined to much tighter maching tolerances than in the 80's and earlier, help the builders to attain more desirable performance and durablity results.

 

[MonsterMark]

Our modern day engines are machined to much tighter maching tolerances than in the 80's and earlier, help the builders to attain more desirable performance and durablity results.

And I might add to lower emissions.

5w20 is the way to go unless your car is using oil. Then working your way up the chart, 30 -40 weights makes sense to fill the gaps a bit. Thicker oil seals better and helps with the lubrication (oil stays on the part longer).

Numbers like 5w-20 indicates it is a mutigrade oil vs SAE 30 which would be a straight oil.

The ‘w” actually stands for ‘winter’, not weight.
The 1st number indicates flow at a cold temperature. Lower means the oil will flow better at cold startup which is critical to engine wear. Start your car in freezing temps with too thick an oil and your engine has no lubrication (bad thing). The 2nd number speaks to the characteristics of the oil in hot temps. Again, the lower number equals thinner which is bad when the weather is hot.

So in winter, 5w20 would be preferred. A 10w30 for hot summer driving will also help.

As Roadboss mentioned, the reason car manufacturers like Ford have moved down the scale is due to the tighter tolerances in the engines, hence the need for thinner oil.

Last but not least, use engine oil additives with caution. Yes, they help, but too much is a bad thing.

Btw, I sell the best oil additive in the world.
PM me if you want to get your hands on some.
Used by Nascar and other race groups to prevent engine damage under huge stress. Not magic in a bottle, but is proven to help.

 

[MERIJONS97LSC]

:shifty: Bubbles=oil oil=small small=air air=bad bad=no??? "I'M SO CONFUSED"!!

Water=tub tub=bubbles bubble=fart fart=pew! "BY JOE I THINK I GOT IT"

 

[ground_zero298]

my dad ran dyno and repair for the 32v at romeo, he has me run 5-20 in the winter and 5-30 in the summer. I've noticed no difference in the mileage between the 2. And like was stated before, as you start using oil move up to a heavier wieght. I'm pretty sure the 5-20 was used to get the oil to the top of the engine faster on start up because of the valve train noise on start up. And I guess the 20 wieght was to pull a extra mile or 2 for the mileage ratings. I do have the romeo tech manual for the 32v. not sure if anyone else does. I would ship it to someone if they wanted to post it up on the site.

And as far as additives go, everything I have ever owned and my dad has owned has had nothing but vavloline in it changed at 3000 miles. Not saying vavloline is the best oil but I've never had any problems engine wise in anything. My 150 has 167000 on it, owned since day 1. I redline that truck everytime I drive it. I've beat the hell out of that engine. Never had any mechanical failure in it. Yes I've been through 3 rearends, my share of radiator hoses, and alternators. But their is no knock or ticks in it and it still only uses a quart every 3 thousand. But if i had something supercharged i would definatly have synthetic in it.

 

[shiryu0]

10w40 ONLY here....but i live in the desert