Advantages 10w40 versus 5w30 (semi v fully?) explain?

[essexplumber]

hora said:

Ok, which one is thicker? I assume the 5w30 is thicker?

Whats best for reducing oil consumption- thicker oil so it can't get passed the O-rings?

10w40 is better for cold morning starts as its thinner gets round the engine quicker?

Also- which is better for the engine, semi or fully??


I'm bloody Confused.com

Err? Ones thicker than the other, or something.

[focusboy]

5w30 is thinner, and thicker oil is less likely to get past worn seals as quickly.

Hth a little, Garry

[MondeoMan1981]

Whats the difference between 5w30 and 5w40 - some sites recommending different grades for my car !

[Taita]

What do FORD say (assume mondeo)

[MondeoMan1981]

Taita said:

What do FORD say (assume mondeo)

206 1.4 hdi..... Planning to be in a Mondeo again in the future.... sad eh

[nottyash]

A local Porsche specialist recomend Valvoline racing 20-50
It sound thick, but apparently it works well at reducing oil consumption through bore wear.

Edited by nottyash on Wednesday 7th April 21:47

[checkmate91]

No! Valvoline Racing 20/50 is a thick mineral-based oil for ancient cast iron engines like old chevy v8s, minis and so on (I've got 4x 5 litre bottles in the garage for my ancient mini). Modern tdis need 5/40 or 10/40 (fords 5/30). 10/40 is thicker if this is the answer you're looking for. 15/40 diesel oil is for ancient diesels (peugeot 504, landrovers etc)

[Dr.Doofenshmirtz]

Engines with hydraulic tappets need a thinner oil, 5w-30 in the case of modern Fords etc.
10w-40 is fine for most others.
API/SAE ratings explained here: http://www.carbibles.com/engineoil_bible.html

[LuS1fer]

The Society of Automotive Engineers (SAE) established a numerical code system for grading motor oils according to their kinematic viscosity.

The viscosity of single-grade oil derived from petroleum unimproved with additives changes considerably with temperature. As the temperature increases, the viscosity of the oil decreases in a relatively predictable manner. On single-grade oils, viscosity testing can be done at a cold, winter (W) temperature to grade an oil as SAE number 0W, 5W, 10W, 15W, 20W, or 25W.

The temperature range the oil is exposed to in most vehicles can be wide, ranging from cold ambient temperatures in the winter before the vehicle is started up to hot operating temperatures when the vehicle is fully warmed up in hot summer weather. A specific oil will have high viscosity when cold and a low viscosity at the engine's operating temperature. The difference in viscosities for any single-grade oil is too large between the extremes of temperature. To bring the difference in viscosities closer together, special polymer additives called viscosity index improvers, or VIs are added to the oil. These additives make the oil a multi-grade motor oil.

10W-30 designates a common multi-grade oil. Historically, the first number associated with the W (again 'W' is for Winter, not Weight) is not rated at any single temperature. The "10W" means that this oil can be pumped by your engine as well as a single-grade SAE 10 oil can be pumped. The second number, 30, means that the viscosity of this multi-grade oil at 100°C (212°F) operating temperature corresponds to the viscosity of a single-grade 30 oil at same temperature.

(Stolen from elsewhere)

Modern cars tend to specify a 5w20 but i suspect this is to improve mpg artificially.

[Bonefish Blues]

hora said:

Ok, which one is thicker? I assume the 5w30 is thicker?

Whats best for reducing oil consumption- thicker oil so it can't get passed the O-rings?

10w40 is better for cold morning starts as its thinner gets round the engine quicker?

Also- which is better for the engine, semi or fully??


I'm bloody Confused.com

At a given ambient temperature within a range 10-30 degrees they are the same thickness.

The 5/30 protects better at low temps as it flows more easily, being designed to operate from the lower temp, hence the 5 lower rating. The 10/40 protects better at ambient temps over 30 degrees, since it's designed to do so, hence the 40 upper rating.

Synthetic almost always better than semi.

...if I've been paying correct attention to Oilman these many years!

[Ozzie Osmond]

For practical purposes a good quality oil of either viscosity will be absolutely fine. The thinner 30 weight will give marginally better fuel consumption, but it's mere fractions.

[LuS1fer]

The Mustang recommends 5w30 but I used Mobil 1 0w/40 in it without any problem though have now switched to 5w/30. Difference? Hard to spot. In truth, in the UK, you are not really going to have to worry about the two extremes too much.

Edited by LuS1fer on Thursday 8th April 08:06

[Munkeyfeet]

Ten years ago, a crack oil man was sent to prison by a military court for a crime he didn't commit. This man promptly escaped from a maximum security stockade to the UK underground. Today, still wanted by the government, he survives as a soldier of fortune. If you have an oil problem, if no one else can help, and if you can find him, maybe you can hire... OPIEOILMAN.