i have a 93 sc400 with 103k. is it ok to use 10w-40 oil?

 

not recommended

 

what would happen if i do? could i use it for a car that has 133k?

 

Not recommended, but some people use heavy oil like 10w-40 to reduce oil burning. Use it only if your SC burns oil really bad and you don't want to spend the money to fix it. I'd stick with 5w-30 and just top off the oil once a month. That's what I did with my old car.

 

There is no problem in using 10W-40. Older engines generally need a thicker oil to maintain good compression. Also, they can protect better in very hot temps. The manual actually recommends 10W-30 for my car if you normally see temps above 100F. Now I know that's not too common, but sitting in traffic on a hot sweltering day on 5th Ave in NYC, the temp can get way above that. My Lexus dealer routinely used 10W-40 in my car during the summer months when I used to go to them during the extended warranty period. During the winter months, stick to 10W-30 or 5W-30. A heavier oil may help with slight burning when there is no indication or need for a complete overhaul. I would not go any thicker than 10W-40, however. I use it during the summer months ,July through September, here in NYC and use 10W-30 the rest of the year.. No problems.

Since 10W-40 has the same viscosity rating when cold as 10W-30, it is fine to use in our cars. Just at hotter temps, it is a bit thicker and can offer better protection. There is a reason racing oils are 15W-40 or higher although you shouldn't use something that thick in our cars unless you have a block/oil heater and are always revving like a maniac (which may actually include some on this forum!)

 

thanks for all the info guys. yea it gets really hot here so i'll just stick with 10w-40 for now and when winter comes around i'll switch back to 10w-30.

 

In Australia, there are people who run 15W-50 or 20W-50 in the 1UZ. Personally, for most 1UZs, i think 10W-30 is a good choice for the motor. I was thinking about using Chevron Delo 400 15W-40 diesel engine oil, just for the stronger add pack. I run 10W-30 year round, my car runs fine even during those hot Bay Area summers...

 

I actually have a couple of friends who use diesel engine oil in their Volvos for that exact same reason. I wouldn't do it in my SC, but they have been using it for several years and their cars are still pulling strong, not one problem. Australia can get pretty darn hot. I drove about 60 minutes towards Broken Arrow from Sydney in NSW and wow was it sweltering out there.

 

I agree! 5W30 or 10W30 only.

 

The Australian 1UZ owners manual is pretty simple - 10w30 is the preferred viscosity. In extreme heat, 15w40 or 20w50 is suggested, or in really extreme cold (which you're unlikely to see here) 5w30. I use Mobil 1 10w30.

10w40 is not listed at all.

 

I just use 10w 30 year round

 

I posted the same question in the Toyota MR2 forum since I accidently put it in, a chemical engineer told me its not a good idea due to the additives or something Oil companies do not have to add to 10W-40. Not to mention it will void the engine warranty... take it with a grain of salt though.

 

There are pros and cons to each of those popular motor oil weights and there is no magic weight that works best in all conditions, so pick a weight that you reason would work best.

 

Short answer. yes.

All depends on the climate really. Here in CA, i run 20w50 in my SS. I run 15W40 in my M3 (both of which call for 5w30....)