Real or Synthetic Oil....
 

I have called a number of Lexus dealers to see if they use real or synthetic oil when they do the oil change. Half said real and the other have say synthetic . How can that be? The reason I would like to know is if you need to add oil I am sure it is not smart to mix the 2 types. What really is the correct answer? Thanks...

call the last place that did your oil change or who you bought the car from. if you are that worried, do a whole new oil change.

It is a brand new car so I have no idea if the oil in the car is real or synthetic. Would some dealers put in real oil and other synthetic. That does not seem normal. Seems to me all dealers would follow the same protocol.

The RCF manual and Lexus HQ calls for REGULAR, non-synthethic oil. But on my latest oil change done by me, I used full Mobile ONE SYNTHETIC oil.

If you are truly worried, just change the oil and from this point on you will know for sure.

BTW, how does the SYNTHETIC BLEND oil sold all over the place work? They are a mix of REGULAR AND SYNTHETIC OIL, RIGHT? So, I don't think you can harm the engine by mixing the two types of oil? Anyone know for sure? Or have an opinion?

Good point but if Lexus states regularly oil is used what reason would a dealer change to synthetic ? I will use regular but this baffles me...thanks again.

IDK. Certainly I'm not an engineer nor in any related automotive fields.

From what I've read in the initial brand new engine break in period, the REGULAR oil helps SEAT the RINGS on the pistons. I switched to FULL SYNTHETIC OIL at 15k miles. I think 15k miles is more than enough for initial break in.

On my last oil change at 10k miles, the Lexus dealer OVERFILLED BY MORE THAN LIKE 2 QUARTS. The oil dipstick was more than two inches ABOVE the TOP MARK!!! That Lexus dealer was a SMALL volume dealership and rarely see any FULL "F" cars. A lot of F Sport whatever, but no FULL "F"s. AFTER this episode, I decided to do my own oil changes.

I just think the benefits of FULL SYNTHETIC OIL out weigh any risks, if any. I think the only risk with FULL SYNTHETIC OIL is the additional COST. Since I'm switching to FULL SYNTHETIC OIL at so early in the engine's life cycle, the risk of FULL SYNTHETIC OIL "seeping" into areas previously "plugged up by sludge from REGULAR OIL" is minimized.

Mobile ONE SYNTHETIC OIL is used as INITIAL FILL in some of the world's high performance cars. Surely if there is any potential harm, this would have already surfaced.

Finally over the years I find synthetic oil makes the engine run quieter, smoother, and respond faster. Especially when the ambient temperature goes to either extremes. Maybe it is all psychological. LOL.

It is safe to mix synthetic and non-synthetic oils, even according to Mobil One. So, OP, if you somehow need to add some oil to top off, you're safe with either one. But after your next oil change, make sure keep a quart extra of the same oil used.
My F is now on Motul 300V and I know she loves it! ����

I've read because people will think that if they use synthetic that they can go 10k miles without changing the oil. Lexus doesn't want people going 10k miles without a oil change.

Synthetic viscosity lasts longer, but all oil gets contaminated during use. The contamination is what causes the most damage. Oil that is only changed after 10k miles is going to have more contamination and therefore it's going to wear the engine more. So you can use synthetic if you want, but you should still stick to your 5k changing intervals. It's only going to increase the price of your oil changes. It's not going to provide much better protection than dino oil for 5k miles.

Family cruisers can get by on 10k oil change intervals with synthetic because they aren't being pushed to the limit a lot (usually).

This is what I've heard.

Oil Level Trick
 

Not entirely related, but on my previous LS460, I would use 8.5 quarts of Mobil 1 and 1 quart of Royal Purple. This allowed a clear visual when checking the oil level.

the main indicator that oil is past its useful life is the Total Base Number or TBN. You can get a TBN test when you send an oil sample to Blackstone Labs. Ive done several 10k mile oil change analysis, all wear indicators are fine, some even below average and the TBN numbers were fine on 10k intervals with synthetic. Synthetic have more consistent viscosity on startup and cutting your oil change labor in half is the primary reason to use it. ISF forum has a blackstone analysis thread and they can go 10k, sometimes more easily because of the huge 10qt oil capacity of the ISF/RCF engines

I think Engineering Explained has a good video on the subject.

That's a good video.

But there are many factors to consider about how well your oil is protecting you. Such as are your miles city miles, highway miles, track miles... Is your car mostly in hot or cold weather... How much time passes between your oil changes... etc. You can rest assured that Lexus engineers know all about oil viscosity. They select the type, grade, amount, and mileage between changes that will provide the longest life for your engine at a reasonable cost to you. So long as you change your oil every 5k miles and/or 3 months then you engine will not fail due to a lack of viscosity before you get rid of it. That is unless the oil pump fails, your oil somehow drains, or you keep your car for 200K+ miles (that doesn't mean it will fail at 201k miles).

I wouldn't believe for a second that I know more about our engine than the people who designed it and put it through millions of miles of testing.

Now, if you track your car then you probably want synthetic oil. If you keep it on the street... It's your call and your money.

I'm not saying synthetic isn't better. I'm saying that it's not always necessary. If viscosity breakdown was going to be an issue in 5k miles then Lexus would have you use 0W-40 or something... i.e. they have already engineered the average breakdown in 5k miles.

"You should always go with whatever interval your manufacturer recommends because..."

Because his attorney won't let him say anything else.

I run synthetic in all my stuff. It works longer. I have data to back up my claims. I have run as long at 14k miles on a load of oil including road course track time, and I just recently had the valve covers off to perform the valve lash inspection. Everything looked just fine, and there is zero varnish - none at all - in the heads or valve covers (the most likely place to find varnish in any engine). Cam lobe wear looked perfectly normal. All my UOAs support longer OCIs. I run Mobil 1 in my NA platforms and Red Line in my turbo because Red Line is a Group V oil and turbos are especially hard on oil (IMHO turbos should have a separate oiling system). The results for my IS F are posted here: https://www.clublexus.com/forums/is-...-uoa-here.html.

If anyone else has actual data, I'm happy to discuss. If you "feel" a certain thing is right or wrong, I won't waste my time reading it.

That's some great info and I applaud you for doing it right and getting the oil analysis.

However, unless you intend to keep your car until it dies the point is really moot. Spotty service records will devalue the car. Going 15k miles between oil changes? I wouldn't touch it.

"But a moderator on our forum said it was okay to go 15k miles between oil changes so long as I was using Mobil 1 and he had lab reports to back it up."

Not following the manufacturer's recommended maintenance schedule is not recommended if you are on a lease or ever intend to sell your car at a dealer (you may be able to convince a private party). You personally "might" be able to use the lab results since you are in possession of the lab results and they were done on your specific car. But anyone else reading this thread is going to have a hard time getting full value for their car if they only change the oil 6 times in 100k miles and try to use your post as their evidence that the car is fine.

I'll keep using dino oil and changing at 5k intervals as per the manufacturer's recommendations. The effect that service records have on the value of your car is not a feeling, it's a fact.

the Lexus RC F 5.0L 8 -cyl Engine 2UR-GSE gets free service for first 20,000 miles or 2 year. 6month or 5000 mile oil changes required for warranty. Lexus sells BRAND quality and service not just a car.

The reason is "safety". They want to look at the car, not so much change the oil. High sump level of 9.8 qts is for cooling.

5w30 is recommended and synthetic is not restricted for use. 10w30 may be used but next oil change they want it back to 5w30. They are responding to most gearheads thinking higher vis is better. They don't want warranty engine failures from gummed up slow flow 20w50 racing oil. Especially when its run hard ( or why buy this heavy pig).
Sounds like marketing is trying to make the buyer feel special about the car, more than anything else and 10 qts of synthetic is higher service cost thus not requiring a synthetic 5w30. Note it also compensates for volatility if run very hard in that 6 months or 5000 miles.

Betting dealers are the ones pushing non synthetic because it costs them less and they get more Lexus corporate take since they get paid a flat rate anyways.

I test oil for a living.

Also, try this.....call a lexus service department, most of them become shocked when they hear the F is run on conventional and not 0W-20.