Motor oil question.

tyr_shadowblade

tyr_shadowblade

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Running an Olds 307 from an '82 or '83 Toronado in my trike.

The builder said he always used 10W40 in the crankcase.

Just had the trike in the shop for the past 2 days, replacing all the fluids and filters and having some other work done (belts and hoses were done last month).

Told the guys to put 10W40 in the crankcase, but apparently they forgot and used the stock oil, which is Valvoline 5W30. A can of BG MOA detergent was also added (at my request).

Question: What possible difference will switching from 10W40 to 5W30 make?

I intend to purchase 5 quarts of high mileage 10W40 prior to my next oil change -- which I'm probably going to have done within 500 miles -- but I wanted to know what I might expect in the meantime, aside from a higher likelihood of leakage?


Thanks.
 
Technically,the engine should crank a little easier on a cold morning but it's doubtful that you'd be able to tell a difference.Valvoline is good oil,I prefer Pennzoil myself but there is very little difference in any of the major oil companies products.If you were spending a lot of time idling in traffic or driving for hours in 100 degree heat,then I would opt for the 10/40,otherwise the 5/30 will work fine.
 
i would say very little or no difference, imho its good to run heavier oil on high mileage engines (like 10-40 or 20-50) but it really doesnt make much difference.

if it was a really old engine with a lotta miles a heavy oil like straight 40 weight might be good due to increased space between the bearings, but still wont make a lotta difference.
 
the higher the number the higher the viscosity (how thick it is). The low number is the viscosity when hot, the high number is the viscosity when cold.

Low vicosity means easier starting, high viscosity when hot means the oil runs off surfaces faster.

Leave it to the manufacturer to decide what is best and stick to it.
 
depending on your oil pump, the lighter oil may not produce enough oil pressure at high temp/ low speed. if you have a pressure gauge, no prob, if you don't I'd definitely switch to the heavier stuff
http://en.wikipedia.org/wiki/Motor_oil#Multi-grade
I'd personally stay away from straight weight oils. I don't see the benefit, and the milti's preform better.
 
gadgetgeek said:
depending on your oil pump, the lighter oil may not produce enough oil pressure at high temp/ low speed. if you have a pressure gauge, no prob, if you don't I'd definitely switch to the heavier stuff
http://en.wikipedia.org/wiki/Motor_oil#Multi-grade
I'd personally stay away from straight weight oils. I don't see the benefit, and the milti's preform better.
Click to expand...

If your oil pressure is low,it's because of to much clearance between the bearings and crank and while heavier oil will make it LOOK better,it isn't.

As far as straight weight oil,it's works fine in an area where there aren't big temperature swings but if your in an area where it's 10 degrees in the morning and 30,40 or more later in the day,the multi weights are better.
 
Andrew Taylor said:
The low number is the viscosity when hot, the high number is the viscosity when cold.
Click to expand...

I think that's the wrong way round.

From Motor Oil at Wikipedia

" Multi-grade
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 VIIs are added to the oil. These additives make the oil a multi-grade motor oil. The idea is to cause the multi-grade oil to have the viscosity of the base number when cold and the viscosity of second number when hot. This enables one type of oil to be generally used all year, and when multi-grades were initially developed, they were frequently described as all-season oil. The viscosity of a multi-grade oil still varies logarithmically with temperature, but the slope representing the change is lessened. This slope representing the change with temperature depends on the nature and amount of the additives to the base oil.

The SAE designation for multi-grade oils includes two grade numbers; for example, 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. "5W" can be pumped at a lower temperature than "10W" and "0W" can be pumped at a lower temperature than "5W". 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. The governing SAE standard is called SAE J300. This "classic" method of defining the "W" rating has since been replaced with a more technical test where a "cold crank simulator" is used at increasingly lowered temps. A 0W oil is tested at −35 °C (−31 °F), a 5W at −30 °C (−22 °F) and a 10W is tested at −25 °C (−13 °F). The real-world ability of an oil to crank in the cold is diminished soon after put into service. The motor oil grade and viscosity to be used in a given vehicle is specified by the manufacturer of the vehicle (although some modern European cars now make no viscosity requirement), but can vary from country to country when climatic or mpg constraints come into play. "

--
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A lot will depend on the manufacturer of the oil. As an example, Mobil 1 10W40 will shear within a month or so, ending up as a 5W30. UOA's have shown Mobil 1 5W30 to effectively have 0W20 properties after just a thousand miles or so.

All the answers you could possibly want on oils, grease and lubrication can be found at www.bobistheoilguy.com. These guys are anal oil nuts! Be sure to check out the section on additives. What you'll see will have you rethinking any additives.
 
beau, with a gear type oil pump, thinner oils may not pump through, I had this problem with my VW jetta, but it was an old worn out beast. it just would not pump hot 5w30 so I ran an odd mix of 15/40 and whatever else I could scavenge. did wonders for the engine.
 
depending where you live, 5/30 is fine for winter months, things get interesting in summer months with thinner oil like that. One of the potential issues is not only is it 5/30 but you added a cleaner. You may star experience oil consumption. Thin oil and cleaner may act like pure synthetic oil. Anyone who has a older car who is use to running with dino oil switching to pure synthetic will see huge amounts of oil consumption. Essentially what happens is that cleaner or synthetic oil does such a good job at cleaning out your engine that you star to get leaks. All that gunk that has built up over time was sealing up all those leaks and when you clean it out you can guess what going to happen. If you want to clean out some of the gunk in a less aggressive manner, next time you change your oil have them add about 1/4 of transmission of a bottle of transmission fluid or a 1/4 of quart of oil meant for diesel automobiles or trucks.
 
UnknownVT said:
I think that's the wrong way round.
Click to expand...

From Motor Oil at Wikipedia

I don't think so unless I didn't explain it right? The thicker the oil, the higher the viscosity number. SAE 80 is gear oil and is thick and viscous. SAE 10 is light machine oil and is thin, not viscous.

In the case of an engine oil where temperature is a major factor in lubrication of the bore, and valves, the oil is thick when cold and thin when hot, hence the difference in stated viscosity... 10 when hot (thin), 30 when cold (thick). It is the same oil, but demonstrates different viscosities when cold and when hot using the same oil under different situations.

A specific oil will have high viscosity when cold and a low viscosity at the engine's operating temperature.
Click to expand...

I think this quote confirms what I said or meant to say.
 
I think you've got it backwards. A multi-grade oil shows the Cold Rated viscosity first, and the hot viscosity second.

From your link:

The SAE designation for multi-grade oils includes two grade numbers; for example, 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. "5W" can be pumped at a lower temperature than "10W" and "0W" can be pumped at a lower temperature than "5W". 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.
Click to expand...
 
I think the point of Multi grade is to maintain a similar viscosity throughout the temp range.

Ex. 5W-30
By having a rating of 5 cold it flows well when the engine is initially started and is still cold. Pretty thin stuff. When hot it has a viscosity of a straight 30 at the same temperature. The oil is still thinner than at low temps, BUT and this is important; with the Viscosity index improvers the oil will stay more viscous than straight 5 oil at operating temps.

In review. multigrades like 5W-30 are effectively straight 5 oils at startup and are equivalent to straight 30 at operating temps. In no way whatsoever does that mean it's thicker when hot. It just doesn't thin as much as a straight 5 oil.
 
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