10W30 vs. 5W30, etc.

[MarkV]

So, I went to the dealership and had an oil change done on the 1988 Corsica. Anyway, the car calls for 5W30 but, I see they put in 10W30, will this have any effect? Will it damage anything? I have always been confused as to the difference between the oils!

[cutlasguy]

I've always been a fan of 10W30 and have used it in both my 72 Cutlass and my 89 Caprice Classic. I never had a problem with lifter noise in the 72, but it was only driven in the summer and started up once a month in the winter and never put under load in cold weather. The Caprice, however , was driven year round and, although it had only 30k on the clock, it would tick when run in extremely cold weather until warmed up! I finally decided to check the owner's manual and there it was! Use 5W30 oil! I never had any ticks since I began using the 5W30 oil, even in single digit temps!

[Guest Skyking]

Both my Dodge Ram and my wife's Buick call for 5W30. Never used that weight. I've been using 10W30 since I've owned both vehicles. The Buick has 109,000 and the truck has 143,000. No problems.

[Guest Jim_Edwards]

The only issue that might exist with 10W30 verses 5W30 occurs at initial starting of a cold engine. 5W30 will reach all engine parts just a fraction of a second faster than 10W30. Once an engine has reached operating temperature the thickeners in both will give it the viscosity of a 30 weight oil.

All sorts of discussions can erupt over whether it is better to use an engine lubricant that is prone to clinging to internal engine parts verses pumping to those parts as quickly as possible. The clinging argument had pretty much lost out in the 1960s when 10W40 became pretty much an industry standard over just plain detergent 30W and 40W engine oils.

Even if a car's owner's manual specifies a 5W30 or 10W30 if one lives in the hot in the summer Southwest part of the country it might still be best to use 10W40 during the hottest months to prevent rapid breakdown of the oil and loss of lubricating properties adequate for the engine.

[Dave@Moon]

The only issue that might exist with 10W30 verses 5W30 occurs at initial starting of a cold engine. 5W30 will reach all engine parts just a fraction of a second faster than 10W30. Once an engine has reached operating temperature the thickeners in both will give it the viscosity of a 30 weight oil.

There is one additional consideration. Pumping the heavier oil will reduce fuel mileage and performance when the engine is not up to temperature. It takes about 5 minutes to get an engine completely up to temperature, where both 10W30 and 5W30 oils will then flow similarly. If much of your driving is in shorter drives (5-10 minutes or less), you should see a mild reduction in both performance and mileage (as well as mildly increased emissions owing to the excess fuel consumption).

Bottom line, both oils cost the same amount and the engineers have already done the leg work to determine the best oil weight for a given temperature range (see owner's manual). The dealership has no excuse for using the wrong oil.

[Guest Jim_Edwards]

There is one additional consideration. Pumping the heavier oil will reduce fuel mileage and performance when the engine is not up to temperature. It takes about 5 minutes to get an engine completely up to temperature, where both 10W30 and 5W30 oils will then flow similarly. If much of your driving is in shorter drives (5-10 minutes or less), you should see a mild reduction in both performance and mileage (as well as mildly increased emissions owing to the excess fuel consumption).

Bottom line, both oils cost the same amount and the engineers have already done the leg work to determine the best oil weight for a given temperature range (see owner's manual). The dealership has no excuse for using the wrong oil.

I use nothing but 100% STP in my crankcases because that stuff clings to metal like a magnet. Of course it's a bit hard on the starter and the damn lifters take about 30 minutes to pump up..................Just Kidding!

However, I knew an idiot that did once fill the crankcase on a Jeep with STP because it was burning a lot of oil. Actually towed that thing to Colorado for a hunting trip and needless to say with temperatures well below freezing nothing was going to turn that engine over. Might as well have filled the crankcase with molasses.

[Steve9]

Dave@Moon is on the right track. Manufacturers recommend 5w30 to decrease friction thus resulting in better fuel mileage. 10w30 won't hurt though.

[Guest Bob Call]

I agree with Dave@Moon, the engineers have done the legwork and determined the best oil viscosity for the engine. Newer engines generally have closer tolerances than older thus the move to 5W-20, 5W-30 and 5W-40. Use the weight recommended in the owners manual.

When going to a oil change service and even a dealer service department, emphasize that you want a certain viscosity not their generic 10W-30. The place I go charges $4 more for Pennzoil or Valvoline 5W-20 over their 55 gallon drum Pennzoil 10W-30.

[NTX5467]

There used to be "dual" recommendations for the same engine (i.e., small block Chevy V-8) in different applications. If the engine was in a car or 1/2 ton pickup, the oil spec would be 5W-30, but if the same engine was in a HD2500, then the recommendation would be 10W-30. Same build specs, etc., just that the HD2500 and higher GVWs were not checked for fuel economy as the other vehicles were. Same bearings and rings and such went in each of those applications, back then. But when CAFE started to include the HD pickups, then they, too, received the 5W-30 oil recommendations.

As stated the 5W-30 oil will move easier in a cold engine. I once posed the question of if we really needed 5W-30 in our more moderate North TX winters, with the orientation that the two oils were too close to really make a difference. When I was using 20W-50 Castrol GTX in my Camaro (back when it was much newer!!), if the temps got below about 30 degrees, on initial start-up in the cold mornings, one lifter would click about three times after the oil light went out (as soon as it started). Other than that, things were quiet.

Anyway, in my research, I went to WalMart and genly shook the bottles of oil. Even at room temp, the 5W-30 oil was "looser" than the similar 10W-30 oil was. The Pennzoil rep stated that the 5W-30 oil was quicker to pour, at room temperature, although the lower number is for 32 degrees F viscosity.

As mentioned, the lighter oil pumps easier and quicker upon initial start-up. Seems like the 0W-30 oils got to the vital engine parts 33% quicker than 10W-30 did, according to one source when the "0W-" oils first came out?

Regarding emissions testing and fuel economy . . . the sooner the oil gets the engine lubricated the more stable the initial start-up activities will be. This means potentially less fuel used and the resultant fewer exhaust emissions in the critical initial cold start situation. The manufacturers also must advocate the use of the same oils and such which were in their engines when they were certified for emissions compliance and fuel economy ratings.

Many "quick lubes" used to keep only 10W-30 oil for their "normal" customers IF they were in the warmer areas of the country. This was before 5W-30 recommendations became so wide-spread. Usually, there were no problems with the 10W spec rather than the 5W spec.

But as fuel economy issues are more intense now, more vehicle OEMs are recommending "5W-" oils. Some are also recommending 5W-20 oils, which usually go into engines with "camshaft phasers" for their Variable Valve Timing components. Using a different viscosity oil can reputedly affect the operation of those components, which could affect engine fuel economy, power, and emissions all in one feld swoooop . . . to a certain degree. Someone who's attuned to their vehicle and the way its engine acts might notice the difference between 5W-30 in the crankcase and 10W-30, but the average person might not, which is why some of the lube centers only have 10W-30 . . . but considering the greatly increasing number of vehicles which have recommendations for 5W-30, that should be changing.

And now GM Dexos1 has somewhat cloudied the waters, with its spec of not only viscosity of 5W-30, the newer "SN" oil designation, but also a somewhat unique additive package than other non-Dexos rated oils. We sell it to one lube center, in quart bottles, by the case. They use it in the vehicles for which it's recommended. If questioned, they point to the owner's manual recommendations as justification for using it rather than the less expensive "bulk" oil they have.

So, factory recommendations of API oil rating, manufacturer "approvals", AND the recommended viscosity rating. Be sure to ask to make sure you're getting what you need to be getting. One of our tool vendors doesn't want "bulk oil" from anybody, but wants to see the oil for his vehicles poured from bottles, to ensure he's getting what he's paying for.

Just some thoughts,

NTX5467

[Dave@Moon]

Newer engines generally have closer tolerances than older thus the move to 5W-20, 5W-30 and 5W-40. Use the weight recommended in the owners manual.

Most new Toyotas and some Hondas & Fords now come with 0W-20 oil, usually with recommended oil change intervals of 10K miles.

[Restorer32]

Customer of mine put an excess of STP or a like product in the engine of his car hauler he used to haul his show car to Hershey. Saturday morning at Hershey we woke before dawn to start the truck and get the truck out of the flea market and the very early car it contained onto the show field. The temp that morning was 27 degrees. The truck would start, run a few seconds and shut off. Did that maybe 5 times before I realized it wasn't just the cold. Checked the dip stick and the oil was like tar. The truck would start, run a few seconds before the low oil pressure switch shut off the ignition. Took maybe 20 tries before the oil warmed up and the pressure gauge started to move. We eventually got it started and got the car onto the show field. More is not always better. I would have drained and refilled the thing before attempting starting it again but the owner was adamant...the show must go on.

[Matt Harwood]

I have to admit that I was always of the school that "thicker is better."

However, when racing my Mustang, I ran 20W50 Mobil 1 thinking that the heat and abuse would benefit from the thicker oil (which thins at high temps). I also discovered that the oil pump drive shaft would twist at high RPM with the thick oil and narrowly avoided a catastrophic failure when it snapped. Back to the recommended 10W30 and no issues since.

I felt the same on my '05 Audi allroad with the 2.7 turbo engine. Everyone said to run 0W30 in it, but I ignored that advice, preferring the thicker 5W30 or even 10W30 in the summer thinking somehow it was "safer" in the turbocharged engine. In the cold weather, there was an awful lifter tick and the turbos sounded a little wheezy. So I put in the recommended 0W30 this winter and it runs like new and is notably smoother.

That puts me solidly in the camp of not trying to out-think the OEM engineers--they're not doing it to cut corners, they're doing it because they know what their machinery needs to run best.

That said, I doubt 10W30 versus 5W30 will make any difference in a car like the Corsica. You're fine.

[Restorer32]

There is more oil in a quart of single viscosity than in a quart of multi viscosity.

[Dave@Moon]

. . . but considering the greatly increasing number of vehicles which have recommendations for 5W-30, that should be changing.

The newest car I've seen a manufacturer recommend 10W30 for was a 2000 Hyundai. Even my 1996 Ranger (a relatively crude truck engine) is recommended to use only 5W30. My 1996 Pontiac Grand Am is only recommended to use 10W30 above 30 degrees F, but 5W30 is an all-temperature recommendation.

In other words 5W30 has been a base oil standard in the industry for at least 10 years.

Does anybody have a 'regular" car (not a heavy duty or performance model) newer than 2000 that is still recommended (or is even permitted by the owner's manual) to use 10W3)? :confused:

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BTW, hybrids are much more sensitive to this than other cars. My father's old 2006 (since traded in on a Prius) hybrid Civic came with 0W20, but the manual also allowed 5W20 with 0W20 being "preferred". He changed to 5W20, mostly because it was cheaper (0W20 was just introduced, and very hard to find at the time). He had a 4 mpg drop in fuel mileage.

[Larry Schramm]

Does 0 viscosity oil have the same viscosity as water?

[Guest Jim_Edwards]

Does 0 viscosity oil have the same viscosity as water?

In simple terms, NO! Also in simple terms, viscosity is the resistance to flow and the viscosity of various liquids will change with various conditions that may affect flow.

[Dave@Moon]

As I understand it, the numbers are used to designate an arbitrary standard for viscosity at a given temperature, with the "W" (winter) flow test conducted at a low temperature (0 degrees F). The higher number is for the flow test performed at 212 degrees F. The oil viscosity is measured by determining the time it takes a given volume to flow (by gravity) through a specified orifice. This online document lists early standards for temperature and flow:

http://www.ideas4ag-ed.com/uploads/3/7/0/4/3704787/stan_toepfer_understanding_motor_oil_viscosity.pdf

[Larry Schramm]

I understand viscosity and how it is measured, but the question is there an arbitrary standard for comparison like water? Is the oil placed at a specified temp for flow and that flow compared to ____what___?

[Dave@Moon]

I understand viscosity and how it is measured, but the question is there an arbitrary standard for comparison like water? Is the oil placed at a specified temp for flow and that flow compared to ____what___?

As far as I know just times on a chart that (with modifications) dates back to 1911.