scottw

Just bought my car and it needs a oil change. What type of oil do you guys recommend? I have always used 10W30 in my truck.
I live in TN so we have a pretty mild winter.

Alwyn678

10w40 for me in winter(ga) 20w50 summer


[Modified by Alwyn678, 10:48 AM 12/21/2001]

scottw

Thanks

79MakoL82

Depends on the condition and mileage on your engine. I have over 100,000 miles and live in Florida, so I run 20W50 all year long. If you have a lot of miles on your engine, I would agree 10W40 for winter and 20W50 for summer sounds about right for TN, but if you're engine has fewer miles or has been re-built, you may be able to go a little lighter.

noskillz

I had always thought to use as light an oil as possible like 10w30. Heavier oils do not lubricate as well ( more viscous ) and they require more gap between parts to flow in volume. Certainly would not want to go from a lighter oil to a heavier then back to lighter. The engine will wear to a larger tolerence with the thick oil then when you switch back to a light oil you could have trouble as the spaces will be too big.

Alwyn678

Boy that is one that I have never heard and I thought I had heard them all :jester

79MakoL82

Lighter oils do flow better, especially in colder weather. But again, it all depends on the condition of your engine and your climate. If you have a lot of miles on your engine, there is already some wear, and therefore a heavier oil can be used to "plug up" those gaps and provide the necessary lubrication. Otherwise, you may end up burning more oil than lubricating. Also, in hot climates where you have high temps and humidity, this can break down the viscosity of the oil to a level that is too low. You need the oil to be viscous enough to adhere to the parts long enough to lubricate. So, in hotter weather, you want to run a heavier oil. In colder weather, you want a oil that can still flow in low temps. So, depending on your climate and the condition of your engine, you select your oil. In a hot climate with 100,000+ miles, you may want to run 20W50 year round. In a cooler climate with a 100,000+ mile engine, you may want to run 10W40 in winter and 20W50 in Summer. If the engine has low miles, you may run 10W30 in winter and 10W40 in summer.

It all depends

Rockn-Roll

If you are interested in oil specifications and which oil to use then go to Pennzoil.com . Also take a look at the owners manual for your vette. It has a chart indicating which oil to use.

I always run 20W-50 unless the temperature is going to drop below -20ºC or -4ºF. I don't think TN gets that cold. I would not recommend altering the oil viscosity ratings between changes unless you are going to change the filter each time. A safe choice for continental USA is 10W-40. If you like to rev it up then perhaps a 20W-50 would protect your engine better since it will be more viscous at higher temperatures. If you want more protection for cold starts then take a look at the synthetic oils which are available with a 5W-50 viscosity.

Briefly from my research oil is there to lubricate, wash away any dirt, and to form a compressed layer inside main and cam bearings so that the parts never hit metal to metal. Each of the viscosities for detergent oils such as all the motor oils will lubricate and wash away dirt, but the viscosities are a good indication of how well they maintain the compressed layer in the bearings. The viscosity also tells you how easily it will flow at colder temperatures. Ideally you want the oil to be the same viscosity throughout the entire operating range of the engine, but you might as well change your oil in your dreams cause you won't get this in reality. The viscosity ratings are a relational comparison with a standardized sample of oil. The first number is its viscosity at -20ºC (-4ºF) and the second number is its viscosity at 100ºC (212ºF) when compared to the sample. For example, a 10W-40 oil has the same viscosity as an SAE 10W oil at -20ºC and the same viscosity as an SAE 40W oil at 100ºC, this is called holding it's viscosity cause normally a SAE 10W oil would be way too thin at 100ºC to stay inside the bearing caps and would get squeezed out, but a 40W oil would be fine, and a 50W would be even better at 100ºC. However, a 50W oil would be too thick at -20ºC and may not even flow into the bearings using the stock oil pump thus resulting in dry bearings until the oil heats up which causes excessive wear. Thus the industry has discovered a means to create an oil that holds its viscosity better, and thus you need to research the oils to see what the specs are for your area to make sure you use an oil that is thick enough for higher temps, and low enough for the coldest temps in your region.

A note on synthetics: In my research I found that the synthetics do lubricate better than fossil fuel oils, but they don't have the coehesion that fossil fuel oils do and at higher temps the synthetics tend to squirt out of the bearing caps before the fossil fuel oils having the same viscosity ratings.

A note on racing oils: I use racing oil when I can afford it. It has better engine cleaning components to keep your engine clean. But, it requires you to change your oil twice as often and it costs twice as much as conventional motor oil. I suggest changing the oil when it gets dirty, and racing oil gets dirty after about 1,500 miles or 3 months which ever comes first.


A note on changing oil: You should check your oil at least once a month, and when going on a drive for over 100 miles. If the oil is low then you should change the oil, not just add some and let it go like that. If you lost some oil then it may be due to contaminates in the oil so add some to bring it up to level only so you can go to the store for more oil. You should change the oil when you can not see through it to the dip stick. You should also change your filter every time you change your oil. The filter can hold up to a quart of dirty oil and will require you to change your oil more often. In the long run an oil change will last longer and protect your engine better if you change your filter each time.

Hope this helps.

UKPaul

Yes, in hotter weather you want to run a heavier oil (unless you're only doing very short journeys). I swap between 10/40 in cold weather to a straight 50 weight in hot weather. This is in an air cooled engine where temperature differences are more noticeable. The "feel" of the engine is much better in the summer when using 50W than it is with 10/40.
For water cooled engines, the advice I got from a chemist working at a large oil company (developing engine oils) is this:
Once a water cooled engine is up to temperature it should stay at around that temperature, so the grade of oil should be the same whatever the season, if the cooling system is in good health (as long as you don't live in the arctic or idle for long periods in Death Valley). The thinner oil is for protecting the engine during the warm up period, when a thick oil wouldn't be able to lubricate as efficiently as splash fed componants may get starved of oil.
This advice applies to engines in good condition. If they are a bit worn then run a heavier oil as mentioned above.
I've followed this advice & my daily driver still sounds OK after 8 years of general neglect & abuse :)
:cheers:


[Modified by UKPaul, 6:36 PM 12/21/2001]

Frank75

I run 10W-40 in my bikes and 10W-30 in all our cars. Years ago I used to run 20W-50 in all my motorcycles, theory being that I needed an oil that was more viscuous, blah, blah, blah. One of the bike magazines did some testing (it was either Joe Minton or Kevin Cameron) on MY bike (1982 1100 Suzuki) investigating oil viscosity and 20W50 ran 10-degrees hotter! Their theory was that higher pumping loads heated it up. I switched back and noticed the bike ran smoother at lower revs.

UKPaul: sounds like an old Brit bike that you're running straight 50 in? I remember one of my friends taking about 10 minutes to warm up his E-Jag because he was running 50-weight. We thought it was cool and because it must have the motor-from-hell in it or something; today I understand that it was just that the oil was so hard to pump that if he didn't warm it up he couldn't even get the clutch out. I wonder if you're not doing yourself a disservice. FWIW, I switched from 20W-50 to 10W-40 on an old Triumph and enjoyed better performance.

Rockn-Roll

Just a note: My 75 vette owners manual warns against driving for an extended distance on 10W30 at freeway speeds. 10W40 is the minimum viscosity for freeway driving.

Techno

One way to simplify is what is your oil pressure? IF you think its to low then go to a higher weight. IF already too high, then drop down.
The lower the weight. the lower the outdoor temp you can run and may limit highway driving. I mean this from the prospect that you may not be able to drive on hot days.
I have stopped using winter grades since straight 30 meets my needs.
If you don't need a heavy oil don't bother with it.

VolVette

The manual that came with my ZZZ crate engine said only to use 5W-30. I have used Mobil 1 Synthetic 5W-30 and have had no problems and the engine sounds great.

No one has mentioned using 5W-30, why?

SES

scottw

Thanks for all the advise. I changed my oil at lunch today and used 10W40. I think it was quite awhile since the last owner changed his oil. It was pretty dirty. Next step is to change the fuel filter. I'll take care of that and flushing the radiator tomorrow.
The weather is finally good and I don't have to work tomorrow so I can take it out for the first time. Can't wait!!!

69er

I believe 5w30 is for the tighter tolerances of todays engines along with a so called fuel savings benefit.
I go with 10w40 in my '69.

Rockn-Roll

Different engines require different oil viscosities. Most C3's have the 350 or 454 with a couple of 390's, 327's and 308's in the bunch. All of these engines use the same engineering when it comes to bearing clearances and such. Newer engines like your ZZZ have tighter tolerances now available with the use of CNC machining, and bearing skirts are wider to help deter oil from squirting out of them, etc. etc.. Mobile 1 is a good choice according to the number of pro racers that use it. You might also like to look at the Mobile 1 synthetic racing oil if you really want to keep the power where you want it.

gearheadz

390's, 327's, 308's?? What the *&^% are you talking about?

Techno

Your owners manual should have a chart and temperture range for the oils. I remember 5w-30 falling under the seasonal use. Check a new car manual to be sure.

UKPaul

Frank, Yup it's an '81 Triumph 750. It definately runs better in hot weather when run on 50W oil (I've even fitted an oil cooler as well!). Being an oil-in-frame model the oil seems to run hotter than the earlier oil tank models. What convinced me was riding along the Mediteranean coast in Spain when it got so hot that the oil pressure warning light started flickering on at 80mph :eek: At the time I was running 10/40 in it (all I could find in Spain) but changed to 20/50 when in France & it ran much better. I only run 50W in the height of summer here (somewhere between the 10th & 12th of August!) when doing long journeys & don't bother waiting for it to warm up - I just start it up & go. If I start doing frequent short trips or the weather cools down significantly I just drop about a pint of 30W in there to ensure good lubrication when cold. I've been doing this for a few years now & the motor still runs well.
The *** bikes of that era (haven't a clue about modern stuff) run best on 10/40 & everybody I know with that age of *** bike uses 10/40 - even with Turbos fitted. The oilways on a Triumph are of a larger cross section than a comparable *** engine so maybe a thicker oil passes more easily?
Happy new year!!
Paul