Vehicle is a 2000 dodge ram 1500 V6 auto tx.
The temps here go from low of 72 to high of 92 and an average of 82…no wild swings in temp or hard starting on cold mornings.
Question… what grade of oil is best…we have multi and single grades available… single grade is cheaper and do you really need a multi grade?
Whatever the owner’s manual says. I suspect it will be 5w-30. I guess you could probably get away with a straight 30 but I wouldn’t-- I’m sure it’s not THAT much cheaper and it won’t circulate as well while your truck’s warming up. Using the proper oil is pretty cheap insurance.
Those temperatures are not exceptional. The answer to your questions would be in the owner’s manual. Likely it will be 5w30 or 5w40 or maybe 10w 30 or 10w40.
The first number is the single weight equivalent when the oil is cold and the second is the single weight oil equivalent when the oil is hot. The higher weight offers better protection when very hot but it also reduces mileage. Your best choice is what is in the owner’s manual as each engine is different and and has different oil needs.
If the temps never drop below 72 then you can probably use straight weight oil. Straight weight oil is usually MUCH better then multi-grade. It’s PURE oil. No viscosity improvers (which really don’t make good lubricators). There shouldn’t be a problem with startup IF the temps don’t drop below 50.
I would stay away from straight grade oils; the first viscosity number is the STARTING viscosity, which is considerbly lower than any operating temperature.
I lived in the tropics for 5 years and most cars had 20W50, since idling in city traffic drove the underhood temperature up dramatically, especially since the A/C was always on.
Your owners manual would have the oil for the highest ambient temperatures listed. In the absence of that information, I would use a 15W40 which has a wide enough range and will ensure easy starting and long engine life. It’s the oil favored by truckers who get 400,000+ miles easily before having to do any engine work. Since fuel economy drives most engine oil recommendations now, I would stay away from any oil starting with 0W… or 5W…, unless it is a full synthetic.
Mike was right about the early multi-grade oils, but modern multi-grade oils are great. Far different than the early versions.
Straight 30 or 40 HD oil will serve you best in hot climates. No need for multi-grade.
I’m not saying multi-grade oils are bad. I’ve been using them exclusively for 30 years. What I’m saying is STRAIGHT oil IS just that…OIL…No additives…just pure oil. 5w-30 oil starts out as 5w oil…then as it gets warmer it behaves like a 30 weight oil…it is NOT a 30 weight oil. If I lived in Texas where the temps never drop below 60…I’d surely use 30w.
I would stay away from straight grade oils; the first viscosity number is the STARTING viscosity, which is considerbly lower than any operating temperature.
If the temps never drop below 72 (As the OP stated)…how is multi weight oil BETTER then 30w?? 30w flows fine at 72.
20w50 is really 20w oil with additives to make it ACT like 50w oil when hot. The long chain polymers it uses to make this happen aren’t particularly good lubricants. If I lived in the tropics…I’d use straight 40w.
I’d go with the recommended multi-grade for warm weather. The engine is still heating up from 72 to over 200, so it sees significant temperature swings.
The 40 or 50 equivalent weight is needed to accomodate the very high operating temperatures. These straight weights are too thick for rapid lubrication during 72F starts. The Viscosity Improvers (VIs) keep these multigrade oils from thinning out, and ensure good film strength at high temperature. Therefore, a 20W50 or 15W40 is normally the preferred oil in moderate to warm climates for easy and low wear starting and long engine life.
Locomotives, Marine and stationary diesels use straight grades, since a locomotive, for instance, may only need to be started once a YEAR! Truckers don’t like straight grade oils. Marine and other diesels often have heaters to warm up the lube oil before cold starts.
May years ago, viscosity improvers were not too reliable, and some engines burned out at high loads. This prompted some operators to swear off multigrade oils.
Very few car manufacturers now even list straight grade oils, knowing the damage that can result from cold starts with heavy grade oils. Toyota only lists 5W30, with 10W30 for emergency use only, if 5W30 is not available.
The 40 or 50 equivalent weight is needed to accomodate the very high operating temperatures. These straight weights are too thick for rapid lubrication during 72F starts.
I disagree with you on that…40w runs FINE at 72 degrees. I think there are very few places in the US someone can actually use a straight weight…especially all year round.
Very few car manufacturers now even list straight grade oils, knowing the damage that can result from cold starts with heavy grade oils. Toyota only lists 5W30, with 10W30 for emergency use only, if 5W30 is not available.
As stated above…very very few places in the US can use a straight weight oil. However…check the owners manual of cars in places like South America…I have…A straight weight oil is the recommended oil…for the same cars and same engines sold here in the US. One big factor for NOT using straight weight is it will lower their Cafe’ numbers.
I’m NOT recommending anyone should switch to 30 or 40 weight oil. A good multi-viscosity oil will keep your vehicle for HUNDREDS OF THOUSANDS of miles. There really is no need to use straight weight. But I sure would IF I lived in the tropics or places like Southern Texas…ONLY if I could even find it. If not I surely wouldn’t worry about it.
It used to be that owner manuals listed several oils. From what I have seen lately they list only one oil. I think that there are two reasons, the oils are better, and drivers are less informed and don’t want to bother to learn how to take care of their cars.